Unit 15 · World History: Empires and Exchange

Picture the city of Kaifeng around the year 1100. Shops stayed open at night. Restaurants served noodles and roast duck. Boats crowded the canals bringing rice from the south. Kaifeng may have held close to a million people, more than any city in Europe would hold for centuries. It was the capital of the Song dynasty, which ruled China from 960 to 1279. Historians call what happened under the Song an economic revolution, and the word is not an exaggeration.

The revolution started in the fields. Farmers adopted a fast-ripening rice from Champa, in what is now Vietnam, that let them harvest two crops a year. More food meant more people. China’s population roughly doubled to about one hundred million by the early 1100s. Fewer hands were needed on farms, so more people could work in towns as weavers, potters, ironworkers and shopkeepers. Song iron foundries used coal and water-powered bellows and turned out iron on a scale Europe would not match for six hundred years.

Trade this large needed money that was easy to carry. Copper coins were heavy, so merchants in Sichuan began using paper receipts, and in the 1020s the Song government printed the world’s first state paper money. The government also expanded the civil service examination, a test on classic texts that chose officials by merit rather than birth. Passing it took years of study, but the exam made learning valuable and helped create a huge market for printed books.

How do we know all this? Song officials kept detailed tax and production records, and painters recorded daily life. One long scroll from the early 1100s, attributed to the artist Zhang Zeduan, shows Kaifeng’s streets crowded with camels, carts, teahouses and a great bridge packed with people. Look at that painting and you see an economy in motion: it is evidence you can read with your eyes.

Muslims called the lands where Islam was practiced Dar al-Islam, the House of Islam. By 1200 it reached from Spain and Morocco across North Africa and the Middle East to Persia, Central Asia and northern India. It was never one empire for long. Yet a scholar in Cordoba and a scholar in Samarkand read the same Quran in the same Arabic, studied the same law and could argue about the same books. That shared culture is what let Ibn Battuta find work everywhere.

The knowledge those scholars shared was vast. In Baghdad in the 800s, the caliphs paid translators to turn Greek, Persian and Indian works into Arabic. Building on them, the mathematician al-Khwarizmi wrote a book on solving equations whose title gave us the word algebra. Ibn al-Haytham, around 1020, showed by experiment that we see because light enters the eye, not because the eye sends out rays. Ibn Sina’s Canon of Medicine, finished around 1025, was used to train doctors in Europe for five hundred years.

Two Chinese gifts helped. Paper reached the Islamic world in the 700s, and paper mills soon ran in Samarkand, Baghdad and Cairo. Cheap paper meant more books, and books needed libraries and schools. A madrasa was a college attached to a mosque where students learned law, grammar, logic and often mathematics and astronomy. Al-Azhar in Cairo, founded in the 970s, still operates today.

Historians read this era through the books that survive, but also through what does not. In 1258 a Mongol army captured Baghdad, killed the caliph and destroyed its libraries. Later writers said the river ran black with ink. That is probably a legend, but the loss was real. Learning did not die; it shifted to Cairo, Damascus, Persia and India. A civilization this widespread could absorb even a blow like Baghdad.

In 1206 a Mongol chief named Temujin united the herding tribes of the steppe and took the title Genghis Khan. By his death in 1227 his horsemen had smashed kingdoms from northern China to Persia. His sons and grandsons pushed on into Russia, Iraq and southern China. The result was the largest connected land empire in history. Its armies were fast, disciplined and merciless: cities that resisted were often destroyed to frighten the next city into surrender.

Once the fighting stopped, something surprising happened. The Mongols were few, and they needed taxes, so they protected trade. They built the yam, a chain of relay stations with fresh horses spaced a day’s ride apart, so messengers and merchants could cross Asia in weeks instead of months. Travelers carried a paiza, a metal tablet ordering local officials to give them food, shelter and horses. Historians call this period, roughly 1250 to 1350, the Pax Mongolica, the Mongol Peace.

Along those roads moved Chinese silk and porcelain, Persian carpets, gunpowder recipes, paper money, astronomers, doctors and missionaries. The Venetian merchant Marco Polo traveled to the court of Kublai Khan around 1275 and stayed for years. Mongol rulers usually let Buddhists, Muslims, Christians and Daoists worship freely, partly because they wanted useful people of every faith at court. After 1260 the empire split into four khanates, but trade among them continued.

The peace had a dark side. The same roads that carried silk carried disease. Fleas on rats in caravans and ships could move farther and faster than ever before. When plague broke out in Central Asia in the 1330s and 1340s, the Mongol network helped carry it west to the Black Sea and on to Europe and the Middle East. The connections the Mongols built made the world richer and, for a few terrible years, deadlier.

A sailor in Aden, at the mouth of the Red Sea, did not need a calendar to know when to leave for India. He needed the wind. Each summer the monsoon blows steadily from the southwest, pushing ships east toward India. Each winter it reverses and blows from the northeast, carrying them home. The winds were so regular that captains could plan round trips a year ahead. That reliability made the Indian Ocean the busiest sea in the world before 1500.

The ships were built for those winds. Arab and Indian shipwrights sewed the planks of their dhows together with coconut-fiber rope and rigged them with triangular lateen sails that could catch wind from the side. Chinese junks were larger, with watertight compartments and several masts. Ports grew where the winds and coasts met: Kilwa and Mogadishu on the East African coast, Aden and Hormuz in Arabia and Persia, Calicut in India, Malacca in Southeast Asia, and Quanzhou and Guangzhou in China.

Each region sold what others lacked. East Africa sent gold from the interior, ivory and enslaved people. India sent cotton cloth and pepper. The Spice Islands of Indonesia sent cloves and nutmeg. China sent silk and porcelain. Along the East African coast, trade created the Swahili culture: city-states whose people spoke a Bantu language filled with Arabic words, built houses of coral stone and practiced Islam. Ibn Battuta visited Kilwa in 1331 and called it one of the most beautifully built towns he had seen.

Archaeology backs up his account. Diggers at Kilwa and at Great Zimbabwe, far inland, have found fragments of Chinese porcelain and glass beads from India and Persia. Chinese coins turn up on Kenyan beaches. In 1405 the Chinese emperor sent Admiral Zheng He with a fleet of hundreds of ships and tens of thousands of men on the first of seven voyages that reached India, Arabia and East Africa. Those voyages ended in 1433, but they showed how far the ocean’s roads already ran.

The Sahara is the largest hot desert on Earth, and for centuries people crossed it the way sailors crossed the sea. The ship was the camel. A camel can carry heavy loads and go days without water, and a caravan of hundreds of camels could cover the roughly two-month journey from Morocco to the Niger River. Caravans traveled from oasis to oasis, guided by people who knew the wells, the stars and the shifting dunes.

The trade rested on a simple exchange. West Africa had gold in its rivers and mines but almost no salt, which people need to live and to preserve food. The desert had salt: at Taghaza, workers cut slabs of it from the ground, and houses there were built of salt blocks. Caravans carried salt south and gold north. That gold ended up in coins from Cairo to Venice. Before 1500 most of the gold in the Mediterranean world came from West Africa.

The state that controlled the gold’s route grew powerful. Around 1235 a leader named Sundiata founded the empire of Mali on the upper Niger. Its most famous ruler, Mansa Musa, made the hajj to Mecca in 1324. He traveled with thousands of followers and so much gold that prices in Cairo were still low years later from all the gold he gave away. A map made in Spain in 1375 shows him seated on a throne holding a golden nugget. His fame had crossed the desert and the sea.

Mali’s wealth also bought learning. The city of Timbuktu, on the desert’s edge, became a center of Islamic scholarship, with mosques, teachers and a busy trade in handwritten books. Ibn Battuta visited Mali in 1352 and praised how safe the roads were and how strictly people kept their prayers. He also complained about customs he found strange. His mixed report is a reminder that a traveler’s view is one point of view, not the whole truth.

Much of what we know about the world of 1300 comes from a handful of travelers who wrote things down. Marco Polo, a merchant from Venice, left for Asia in 1271 and returned in 1295. He dictated his story in a Genoese prison to a writer of romances. Ibn Battuta dictated his to a scholar in Morocco about 1355. Both books were bestsellers in their day. Both are also full of problems. Neither man kept a diary, so they recalled events years later.

So historians corroborate: they check one source against others. Polo described paper money, coal burned as fuel and the yam relay stations. Chinese records confirm all three. That raises our trust in him. But he never mentions the Great Wall, tea or the binding of women’s feet, which makes some scholars wonder how much of China he saw. Ibn Battuta’s description of Kilwa matches the ruins archaeologists have excavated. Parts of his account of China, however, may be borrowed from other writers.

Travelers also carried bias, a slant that shapes what a person notices and how they judge it. Polo measured everything by Venice and marveled at wealth. Ibn Battuta measured everything by Islamic law and was quick to praise piety or condemn its absence. Neither wrote much about the poor, about women’s daily lives or about the enslaved people who rowed ships and carried loads. What a source leaves out is evidence too.

The best way to read these books is with a map, a timeline and a second source open beside them. When Polo and Ibn Battuta and a Chinese official all describe the same port, their agreements are probably true and their differences are worth arguing about. That habit of cross-checking is what turns a good story into history.

In October of 1347 a few Genoese trading ships pulled into the harbor of Messina, in Sicily. Most of the sailors were dead or dying. Swellings the size of eggs had appeared in their armpits and groins, followed by fever, black patches on the skin and death within days. The townspeople drove the ships away, but too late. Within months the disease was in every port of the Mediterranean.

The disease was bubonic plague, caused by a bacterium that lives in fleas carried by rats. It had probably started in Central Asia in the 1330s and moved along Mongol caravan routes to the Black Sea. From there Italian merchant ships carried it west. It hit the Middle East at the same time: Ibn Battuta saw it in Damascus in 1348, and Cairo, one of the world’s largest cities, lost perhaps a third of its people. In Europe the plague spread from Italy to France, Spain, England and north to Scandinavia by 1350.

The numbers are staggering even as rough estimates. Historians think the Black Death, as later writers named it, killed somewhere between a third and a half of Europe’s population, tens of millions of people, in about five years. Whole villages emptied. Florence, a city of perhaps ninety thousand, may have lost half its people. Priests died faster than others because they visited the sick. Chroniclers wrote of bodies stacked in trenches with no one left to ring the church bells.

People searched for causes and found the wrong ones. Doctors blamed bad air or the alignment of planets. Some blamed God’s anger and marched through towns whipping themselves. Others blamed Jews and accused them of poisoning wells; in Strasbourg in 1349 the city’s Jews were murdered on that false charge. The real cause, the bacterium Yersinia pestis, was not identified until 1894. The plague returned in waves for centuries, but nothing matched the first great wave.

Imagine a village where forty of every hundred people died in one summer. The fields are still there, but there are not enough hands to plow them. The lord who owns the land needs workers badly. The survivors know it. That is what happened across Europe after 1350, and it changed the balance of power between those who owned land and those who worked it.

Wages rose sharply because labor was scarce. Landlords tried to stop this. In England, Parliament passed the Statute of Labourers in 1351, which ordered workers to accept the wages paid before the plague. It largely failed; people simply moved to lords who paid more. Serfdom, the system that bound peasants to a lord’s land, weakened in western Europe as peasants bargained for freedom or just walked away. When rulers pushed back with new taxes, peasants rebelled: in France in 1358 and in England in 1381.

The plague also shook belief in authority. Prayers had not stopped the dying; neither had doctors. Some people turned to intense personal religion, and images of dancing skeletons appeared on church walls. Others questioned the Church, which had lost many priests and replaced them with less-trained men. In the Middle East, the historian Ibn Khaldun, whose parents died of plague, wrote that it was as if the world had called out for oblivion and been answered.

Historians debate how much the plague explains. Some argue that fewer people meant more land, food and wages per person, and that this helped fuel the Renaissance and later exploration. Others point out that Egypt suffered similar losses without the same results. The disaster was the same; what people built afterward depended on the laws, land and institutions they already had.

Florence in 1400 was a city of bankers and cloth merchants. Its money came from wool, dye and loans to kings and popes. The Medici family alone had branches of their bank across Europe. Wealth like that bought more than palaces. It paid for tutors, libraries, sculptors and painters. Out of these Italian city-states came the movement historians call the Renaissance, a French word for rebirth, roughly from the 1300s to the 1500s.

What was reborn was ancient Greece and Rome. Scholars called humanists hunted through monastery libraries for lost Latin manuscripts and learned Greek to read Plato and Homer. When Constantinople was threatened and then fell in 1453, Greek scholars fled to Italy carrying more books. The humanists did not reject religion, but they argued that studying history, poetry and ethics could make a person wiser and better in this life, not only the next.

Artists caught the same spirit. In the early 1400s the architect Brunelleschi worked out the rules of linear perspective, a method for drawing so that objects shrink toward a vanishing point as they do to the eye. Painters used it to make flat walls open into believable rooms and landscapes. Brunelleschi also engineered the enormous brick dome of Florence’s cathedral, finished in 1436, a feat no one had managed since ancient Rome. Leonardo da Vinci, born in 1452, filled notebooks with anatomy, machines and flowing water.

The Renaissance did not come from Italy alone. Many Greek works reached Europe through Arabic translations made in Baghdad and Spain centuries earlier. Paper came from China through the Muslim world. The gold that paid for Florence’s art came partly from Mali. Seen from a distance, the rebirth of Europe was one more product of the networks this chapter has been tracing.

Before 1450, every book in Europe was written by hand. A single Bible took a scribe about a year and cost as much as a house. Then, in the German city of Mainz, a goldsmith named Johannes Gutenberg put together a new system. He cast individual letters in metal, arranged them in a frame, coated them with sticky oil-based ink, and pressed paper against them with a screw press adapted from wine making. His Bible, finished around 1455, was the first major book printed in Europe.

Gutenberg did not invent printing. Chinese printers had carved whole pages into wood blocks since the 800s, and Bi Sheng had made movable type from clay in the 1040s. Korean printers cast metal type and used it to print a Buddhist text in 1377. What was different in Europe was the alphabet. Chinese needs thousands of characters; Latin needs about two dozen letters. Movable type fit the alphabet perfectly, and Gutenberg’s metal letters could be reused thousands of times.

The results came fast. By 1500, presses were running in more than two hundred European towns and had printed millions of books, more than all the scribes of the previous thousand years combined. Prices fell. Merchants bought manuals, students bought textbooks, and ordinary people bought pamphlets and prayer books in their own languages. Ideas that once took decades to spread now crossed Europe in months. Within seventy years the press would carry a religious revolt across the continent.

Printing also changed how people thought about truth. When every copy of a book is identical, readers in different cities can argue about the same page. Maps, star tables and anatomy drawings could be reproduced exactly instead of copied badly. Errors could be corrected in the next edition. Some historians argue that this fixed, shared knowledge made modern science possible.

For more than a thousand years, Constantinople had been the capital of the eastern Roman, or Byzantine, Empire. Its triple walls had turned back Persians, Arabs and Bulgars. By 1450 the empire behind those walls had shrunk to the city itself and a few scraps of land. Around it lay the growing empire of the Ottoman Turks, who had crossed from Asia into Europe a century earlier and were now ruled by a young sultan, Mehmed II.

In April 1453 Mehmed arrived with an army far larger than the defenders’ and with something new: enormous bronze cannon, one so large it needed dozens of oxen to move. For weeks the guns pounded the ancient walls. When a chain across the harbor blocked his ships, Mehmed had them dragged overland on greased logs and launched into the water behind it. On May 29, after a siege of about fifty-three days, Ottoman soldiers broke through. The last Byzantine emperor died fighting. Mehmed rode into the great church of Hagia Sophia and turned it into a mosque.

The consequences rippled outward. The Ottomans now held the crossing between Europe and Asia and the sea route to the Black Sea. Italian merchants could still trade, but on Ottoman terms. Greek scholars carried manuscripts to Italy, feeding the Renaissance. And Europeans watched the lesson of the cannon closely: stone walls that had stood for centuries could now be knocked down in weeks. Every ruler who could afford it began buying guns.

Mehmed called himself Caesar and rebuilt the city, which came to be called Istanbul, as an imperial capital open to Muslims, Christians and Jews. Christian Europe called the fall a catastrophe; the Ottomans called it a conquest that God had promised. Both were describing the same day. A historian’s job is to hold both views and explain what actually changed.

Suppose you could stand above the Earth in 1450 and compare its regions. China under the Ming dynasty was the richest and most populous state, with printing, paper money, iron industry and the largest ships ever built. Yet in 1433 the Ming court had ended Zheng He’s ocean voyages and turned its attention to the northern frontier. The Islamic world stretched across three continents, led in astronomy and medicine, and its Ottoman rulers had just shown the power of cannon.

Europe was, in most ways, a poorer and less advanced corner of Eurasia. It imported spices, silk and paper and paid for them with silver and African gold. But it was changing fast. Italian bankers had invented tools for moving money across borders. Gutenberg’s press had just started running. Portuguese sailors, using compasses and lateen sails borrowed from Muslim seamen, had crept down the West African coast and reached the Senegal River by the mid-1440s in search of gold.

Across the Atlantic, peoples that Afro-Eurasia did not know existed had built their own civilizations. In central Mexico the Aztec capital Tenochtitlan, on an island in a lake, was one of the largest cities in the world. In the Andes the Inca were building an empire linked by thousands of miles of stone roads. They had no iron, no horses, no wheeled vehicles and no immunity to Eurasian diseases. Those gaps would matter terribly within a century.

Why does this comparison matter? Because the story that follows, in which Europeans sailed across oceans and built empires, was not the result of Europe being ahead. In 1450 it was not. What Europe had was hunger for Asian goods, new guns and ships, competing kingdoms willing to gamble, and an Atlantic coastline facing the unknown. The next chapter follows what happened when those pieces met the winds.

Portugal is a small country on the western edge of Europe with its back to Spain and its face to the Atlantic. In the early 1400s its rulers had a problem and an idea. The problem was that Asian spices and African gold reached Europe through Muslim and Italian middlemen who took most of the profit. The idea was to sail around them. A prince later called Henry the Navigator, who died in 1460, sponsored voyage after voyage down the African coast.

The tools came from everywhere. The magnetic compass had reached Europe from China through the Islamic world. The astrolabe, refined by Muslim astronomers, let a sailor measure the height of the sun or a star and estimate his latitude. Arab lateen sails let a ship sail closer to the wind. Portuguese shipwrights combined them in the caravel, a small, fast, shallow ship that could explore rivers and coasts and, crucially, sail home against the wind.

Progress was slow and then sudden. Sailors feared the Atlantic’s long westward loops of wind and current, but they learned to use them. By the 1440s the Portuguese had reached the Senegal River and were trading for gold and buying enslaved people. In 1482 they built a fort at Elmina, on the coast of modern Ghana, to guard the gold trade. In 1488 Bartolomeu Dias rounded the southern tip of Africa. In 1498 Vasco da Gama reached Calicut in India and sailed home with spices worth many times the cost of his voyage.

One more piece of the story was planted on Atlantic islands. On Madeira and the Canaries, Portuguese and Spanish settlers grew sugar cane, a crop that needs heavy labor to cut and process. They used enslaved workers, at first from the Canaries and then from Africa. The island sugar plantation, worked by captives, was a small model of a system that would soon spread across the Atlantic on a vast and terrible scale.

Christopher Columbus was a sailor from Genoa who had studied the Portuguese voyages and drawn a wrong conclusion. He believed the Earth was much smaller than it is, so that Japan lay only a few thousand miles west of Spain. Educated people already knew the world was round; they doubted his distances, and they were right. After years of refusals, the rulers of Spain, Ferdinand and Isabella, agreed in 1492 to back him with three small ships.

On October 12, 1492, after about five weeks at sea, his crew sighted an island in the Bahamas. The people who lived there were Taino, farmers and fishers who grew cassava and corn and lived in villages under chiefs. Columbus wrote that they were generous, wore little gold, and would make good servants. He claimed their land for Spain, took several of them captive as interpreters and sailed on to Cuba and Hispaniola. He died in 1506 still insisting he had reached the edge of Asia.

Spain and Portugal quickly divided the world between them. In the Treaty of Tordesillas in 1494 they drew a line down the Atlantic: lands west of it would be Spain’s, lands east Portugal’s. No one asked the people living there. Spanish settlers on Hispaniola forced the Taino to dig for gold and grow food under a system called the encomienda, which gave a Spaniard the right to the labor of a group of Indigenous people in exchange for teaching them Christianity.

The result was collapse. Overwork, hunger, violence and above all diseases like smallpox, to which the Taino had no resistance, killed them by the tens of thousands. A Spanish priest, Bartolomé de las Casas, who had once held an encomienda himself, later wrote that of the hundreds of thousands living on Hispaniola in 1492, almost none were left within a few decades. His numbers are debated. The disappearance of a people is not.

In 1519 Hernán Cortés landed in Mexico with about five hundred men and a handful of horses. Two years later Tenochtitlan, a city of perhaps two hundred thousand people, lay in ruins and its ruler was dead. In 1532 Francisco Pizarro, with fewer than two hundred men, captured the Inca emperor Atahualpa at Cajamarca and within a few years controlled an empire that stretched two thousand miles along the Andes. How could so few defeat so many?

The first answer is that they did not do it alone. The Aztec ruled by force over many peoples who paid them tribute and hated them. Cortés made allies of the Tlaxcalans, who sent tens of thousands of warriors against Tenochtitlan. Most of the army that took the city was Indigenous. In Peru, Pizarro arrived just after a civil war between two brothers for the Inca throne had torn the empire apart. He captured Atahualpa by treachery at a meeting, held him for a room full of gold, and then executed him.

The second answer is disease. Smallpox reached Mexico in 1520 with a Spanish expedition and swept through Tenochtitlan while it was under siege, killing the emperor Cuitlahuac and perhaps a large share of the city’s people. It reached the Andes before Pizarro did, killing the Inca emperor Huayna Capac and setting off the civil war. An enemy that could not be seen did more to break these empires than any weapon.

Weapons did matter. Steel swords and armor, crossbows, a few cannon and above all horses gave Spanish soldiers advantages in open battle, since the Americas had no iron and no large riding animals. Cortés also had ships built to control the lake around Tenochtitlan. Yet the Aztec adapted quickly, and Indigenous accounts written in Nahuatl in the decades after describe fierce resistance, not a people paralyzed by awe. The conquests were real, but the reasons were more tangled than the conquerors’ own stories claimed.

Before 1492 no one in Italy had tasted a tomato. No one in Ireland had seen a potato. No one in India or Thailand had cooked with chili peppers. No horse had run on the Great Plains, and no cow, pig, sheep or chicken lived anywhere in the Americas. The two halves of the world had been separated for so long that they had grown different sets of plants, animals and germs. Historians call the swap that followed Columbus the Columbian Exchange.

From the Americas, Afro-Eurasia gained corn, potatoes, sweet potatoes, cassava, tomatoes, peanuts, beans, squash, chili peppers, cacao, tobacco and pineapples. Some of these were more productive than any Old World crop. Potatoes could feed a family from a small plot and grew where wheat would not. Corn and sweet potatoes let Chinese farmers plant hillsides that had been useless for rice. Historians argue that these crops helped populations grow in Europe, China and West Africa in the centuries after 1600.

From Afro-Eurasia, the Americas gained wheat, rice, sugar cane, coffee, bananas, citrus fruit and, above all, animals. Horses transformed life for peoples of the Great Plains and the Argentine pampas, who became mounted hunters within a few generations. Cattle and pigs, running loose, multiplied into the millions. They also trampled Indigenous fields and spread across land that farmers had just been forced to abandon. The landscape itself changed.

The exchange was uneven in who chose it. European settlers brought their crops on purpose. Corn and potatoes crossed to Europe and Asia because farmers found them useful. But many exchanges were forced or accidental: African rice-growing skills traveled with enslaved people to the Carolinas, and earthworms, rats and weeds crossed in ships’ ballast. The most consequential passengers of all, the germs, are the subject of the next lesson.

In Afro-Eurasia, people had lived beside cattle, pigs and horses for thousands of years, and diseases had jumped from animals to humans: smallpox, measles, influenza, typhus. Those who survived childhood carried some resistance, and so did their children. The Americas had few domesticated animals and none of those diseases. When they arrived after 1492, they struck what historians call a virgin soil epidemic: a population in which no one had any immunity at all.

The results were unlike anything in the Old World, even the Black Death. Smallpox alone could kill half of a community in one pass. Measles, influenza and other illnesses followed, often in overlapping waves, so that survivors of one epidemic were weakened for the next. Farmers too sick to plant led to famine. Elders died before passing on knowledge. Populations that had never seen a European fell ill anyway, because the diseases traveled along Indigenous trade routes faster than the Spanish did.

The numbers are debated, because no one counted the population of the Americas in 1491. Estimates range from tens of millions to well over one hundred million. What most historians agree on is the scale of the fall: by about 1600 the Indigenous population had dropped by something like ninety percent. The Valley of Mexico, one of the most densely populated places on Earth, lost the great majority of its people within eighty years of Cortés’s arrival.

We know this partly from Spanish tax counts, which shrank decade by decade. We also know it from Indigenous voices. In the 1570s, Nahua scholars worked with the Spanish priest Bernardino de Sahagún to record, in their own language, what the 1520 smallpox had been like. They described sores that covered people from head to foot. They described the sick who could not move or turn over. They described the many who starved because no one was left to care for them. It is one of the few disasters this large described by the people who lived it.

Potosí, the silver mountain in the Andes, was discovered in 1545. By 1600 the town beneath it had swelled to perhaps one hundred fifty thousand people, larger than any city in Spain. The Spanish crown took a fifth of every bar of silver as tax. To keep the ore flowing, the viceroy revived the Inca system of labor draft, the mita, and required Indigenous villages across the region to send one seventh of their men to the mines each year. The work was brutal, and mercury used to refine the ore poisoned workers slowly.

The silver went two ways. Fleets carried it across the Atlantic to Seville, where it paid for Spain’s wars and drained away to bankers in Genoa and Antwerp who had lent the king money. So much silver arrived that prices across Europe rose for a century, a slow inflation that hurt people on fixed incomes and helped merchants. Spain’s kings spent the money as fast as it came and went bankrupt several times anyway.

The other route was across the Pacific. Beginning in 1571, Spanish galleons sailed each year between Acapulco in Mexico and Manila in the Philippines. There Chinese traders exchanged silk and porcelain for silver. China had a huge economy and little silver of its own, and in the 1570s the Ming government began requiring taxes to be paid in silver. So silver was worth more in China than anywhere else, and merchants bought it there with goods. Historians estimate that a large share of American silver ended up in China, some by way of Europe and India.

This was the first time a single commodity linked every inhabited continent. A drought at Potosí could raise prices in Fujian. A Ming tax reform could change the fortunes of miners in the Andes. Money, in the form of the Spanish peso, became the closest thing to a world currency; it was legal tender in the United States until the 1850s. And all of it rested on the men who climbed down into the Rich Hill by candlelight.

Sugar started it. Europeans wanted sugar, sugar cane grew well in the Caribbean and Brazil, and the Indigenous people who might have been forced to grow it were dying of disease. Portuguese traders already bought captives on the African coast. Beginning in the early 1500s and growing every decade, European ships carried enslaved Africans across the Atlantic. Historians using surviving ship records count roughly twelve and a half million people forced aboard between about 1500 and 1866, of whom about ten and a half million survived the crossing.

The system worked as a triangle. Ships from Europe carried cloth, guns, iron and rum to West Africa. There, at forts like Elmina and ports like Ouidah, they traded these goods to African merchants and rulers for captives, who had usually been taken in wars or raids inland. The ships then crossed the Atlantic on the Middle Passage, a voyage of one to three months in which people were chained below decks in heat, filth and disease. Roughly one in seven died at sea. In the Americas the survivors were sold, and the ships loaded sugar, tobacco or silver for Europe.

Slavery had existed in Africa, Europe and Asia for thousands of years, but this system was new in three ways. Its scale was vast. It was chattel slavery, meaning people were treated as property that could be bought, sold, mortgaged and inherited, and their children were born enslaved. And it was tied to race: over time, laws in the Americas defined enslavement as a condition for people of African descent alone. That link between skin color and slavery was built, deliberately, in these centuries.

Who was responsible? European merchants and governments organized and profited from the trade. So did African rulers and traders who sold captives, sometimes under pressure, sometimes eagerly, and some kingdoms grew powerful on guns bought with human beings. Plantation owners in the Americas demanded ever more workers. Consumers in Europe bought the sugar. The evidence points not at one villain but at a system in which many people found it profitable to look away.

Resistance began in Africa. In 1526 Afonso I, the Christian king of Kongo, wrote to the king of Portugal complaining that Portuguese traders were kidnapping his people, even nobles and relatives of his own family, and carrying them off to be sold. He asked that the trade be stopped. It was not. A century later Queen Nzinga of Ndongo, in what is now Angola, fought the Portuguese for decades, making alliances, leading troops and negotiating until her death in 1663.

On the ships, captives rose up whenever they could. Records show revolts on roughly one in ten slaving voyages, which is why crews kept men chained and mounted guns facing the deck. Some captives refused food. Some jumped overboard. The cost of guarding against rebellion was so high that historians think it reduced the total number of people carried by hundreds of thousands. Every revolt made the trade a little more expensive, and expense was the only argument the traders understood.

In the Americas, enslaved people escaped when they could and built free communities in mountains and swamps. Colonists called them maroons. In Brazil, escapees founded Palmares, a settlement of thousands that survived Portuguese attacks for most of the 1600s before it was destroyed in 1694. In Jamaica, Mexico, Colombia and Suriname, maroon communities fought colonial troops to a standstill and in some cases forced treaties recognizing their freedom.

Most people could not escape, and their resistance took quieter forms. They worked slowly, broke tools, kept their languages and religions alive, and raised children with memories of Africa. West African rice farming techniques, music, foods and beliefs survived and reshaped the cultures of Brazil, the Caribbean and the American South. Survival itself, under a system built to erase people, was a form of resistance, and historians now read the evidence for it as carefully as they read the ship logs.

In 1517 a monk and professor named Martin Luther, in the small German town of Wittenberg, was angry about indulgences. The Church was selling certificates that promised to reduce punishment for sins in the afterlife, and the money was going to build St. Peter’s Basilica in Rome. Luther wrote ninety-five arguments against the practice, in Latin, for scholars to debate. Within weeks printers had translated and reprinted them. Within months they were being read across Germany.

Luther’s ideas went far beyond indulgences. He argued that people are saved by faith alone, not by good works or Church rituals, and that the Bible, not the pope, was the final authority. He translated the Bible into German so ordinary people could read it. When the pope excommunicated him in 1521 and the emperor ordered him arrested, German princes protected him, partly from conviction and partly because breaking with Rome let them seize Church lands. The movement became known as the Reformation, and its followers as Protestants.

The split spread and multiplied. In Switzerland, John Calvin built a strict Protestant community in Geneva and sent trained preachers across Europe. In England, King Henry VIII broke with Rome in 1534 mainly to end his marriage, and made himself head of the English church. The Catholic Church answered with its own reform: the Council of Trent, from 1545 to 1563, clarified doctrine and cleaned up abuses, and a new order, the Jesuits, founded schools and sent missionaries from Brazil to Japan.

Religion and politics could not be pulled apart, and the result was war. France was torn by decades of fighting between Catholics and Protestants, including the massacre of thousands of Protestants in Paris in 1572. The Thirty Years’ War, from 1618 to 1648, drew in most of Europe and devastated Germany, where some regions lost a third or more of their people. The Peace of Westphalia that ended it let each ruler choose the religion of his state. Europe would remain divided, and rulers learned that armies, not sermons, settled the question.

For fourteen hundred years, educated people in Europe and the Islamic world had agreed on one picture of the heavens. The Earth sat still at the center of the universe. The sun, planets and stars moved around it. It matched what the eye saw and what ancient Greek authorities and the Church taught. In 1543 a Polish churchman, Nicolaus Copernicus, published a book arguing the opposite: the sun was at the center and the Earth was a planet moving around it. He waited until he was dying to publish, and few people at first believed him.

The next generation supplied the evidence. The Danish astronomer Tycho Brahe measured the positions of planets more precisely than anyone before. His assistant Johannes Kepler used those numbers to show that planets move in ellipses, not perfect circles, following exact mathematical laws. In 1609 the Italian Galileo Galilei built a telescope and turned it on the sky. He saw mountains on the moon, moons circling Jupiter and the phases of Venus, none of which fit the old picture. He published quickly, in Italian as well as Latin, and printing carried his drawings across Europe.

Authority pushed back. In 1633 the Church put Galileo on trial and forced him to deny that the Earth moves; he spent his last years under house arrest. Yet the method he used spread anyway: observe carefully, measure, test ideas against evidence, and describe results in mathematics. Thinkers called it the scientific method. In 1687 the Englishman Isaac Newton showed that a single law of gravity explained both a falling apple and the orbit of the moon. The universe, it seemed, ran on laws that human reason could discover.

This Scientific Revolution did not happen in a vacuum. Copernicus used mathematical tools developed by astronomers in the Islamic world. Printing let scientists compare identical tables and correct each other. Voyages across oceans had already shown that ancient geographers were wrong about the world, which made people readier to doubt them about the heavens. And the new confidence that nature followed discoverable laws would soon be turned on government and society, as the next chapter shows.

Walk through Mexico City in 1650 and you would hear Spanish, Nahuatl and African languages in the same market. Spanish officials, Indigenous farmers, enslaved and free Africans, and people of mixed descent bought chocolate, wheat bread, Chinese silk and cotton cloth from India. Colonial artists painted series of portraits classifying families by ancestry, a sign of how much mixing had happened and how anxious the rulers were to rank it. This was a new kind of society, born of the exchange.

The Atlantic was now crossed constantly. Sugar from Brazil and the Caribbean went to Europe; cloth and guns went to Africa; captives went to the Americas; silver went everywhere. In 1602 the Dutch founded the East India Company, the first business to sell shares to the public, and its ships soon dominated the spice trade in Asia. Amsterdam replaced Antwerp and Seville as Europe’s money center. Rivalry among European powers over this trade produced wars that were fought on four continents.

Indigenous peoples did not simply vanish. In Mexico and the Andes, communities survived, kept their languages, went to court against Spanish landowners and rebuilt after the epidemics. In North America, the Iroquois, Algonquian and other nations traded furs with the French, Dutch and English, played rivals against each other and shaped how colonies grew. Africans and their descendants built churches, brotherhoods and free towns. The world of 1650 was made by all of them, not only by Europeans.

So who gained and who lost? Europe gained new lands, crops, silver and eventually the wealth that would help fuel its later rise. China gained silver and new food crops. Africa lost millions of people and saw some states corrupted by the trade in captives. Indigenous America lost most of its people and its independence. A student in Illinois today eats corn from the Americas, wheat from Eurasia and chocolate sweetened with sugar first grown by enslaved labor. The Atlantic world is not history that ended; it is the ground we stand on.

By 1550 the Ottoman sultan ruled from Hungary to Iraq and from the Black Sea to Algeria. Suleiman, who reigned from 1520 to 1566, was called the Magnificent by Europeans and the Lawgiver by his own people. He had besieged Vienna in 1529 and nearly taken it. His navy controlled most of the Mediterranean. His empire, with Istanbul at its heart, was the largest and richest in Europe and the Middle East, and it was built on gunpowder.

Historians call the Ottomans, Safavids and Mughals the gunpowder empires because cannon and muskets let them crush older armies and knock down old walls. The Ottoman core was the janissaries, infantry armed with muskets. They were recruited through the devshirme, a levy that took Christian boys from the Balkans, converted them to Islam, and trained them as soldiers or officials owing loyalty to the sultan alone. Some rose to be grand vizier, the empire’s chief minister. It was a strange kind of slavery that could lead to the top of the state.

Ruling so many peoples required flexibility. Most Ottoman subjects in Europe were Christians; many in cities were Jews who had fled Spain after 1492. The empire organized them into communities called millets, each led by its own religious leaders, keeping its own courts and schools, and paying a special tax. It was not equality: non-Muslims had fewer rights. But it was far more tolerance than Christian Europe offered to Muslims or Jews at the time.

How do we know what the Ottoman state looked like from the inside? Its bureaucrats kept enormous registers of villages, taxes and soldiers that still fill archives in Istanbul. Foreign ambassadors wrote detailed reports home. One Habsburg envoy in the 1550s marveled that Ottoman officials rose by ability rather than birth, and warned that his own side, which gave commands to well-born amateurs, would lose. He was describing the empire at its peak; the next two centuries would test it.

In 1501 a fourteen-year-old named Ismail, leader of a religious brotherhood, took the city of Tabriz and declared himself shah of Persia. He did something that shaped the Middle East to this day: he made Shia Islam the official religion of his state. Shia Muslims believe that leadership of the Muslim community should have passed to the Prophet’s son-in-law Ali and his descendants; Sunni Muslims, the majority worldwide, do not. Persia had been mostly Sunni. Ismail’s Safavid dynasty forced the change, and Iran has been mostly Shia ever since.

The Ottomans, who were Sunni, saw the new Shia state on their border as both a rival and a heresy. In 1514 at Chaldiran, Ottoman cannon and muskets destroyed Ismail’s cavalry, which had charged with swords. The lesson was brutal and clear: an empire without gunpowder could not survive. The two empires fought on and off for two hundred years, and the border they eventually settled on runs close to the modern border between Turkey and Iran. Religious difference and imperial rivalry reinforced each other.

The greatest Safavid ruler, Shah Abbas, reigned from 1588 to 1629. He rebuilt the army with muskets and cannon, using enslaved soldiers from the Caucasus much as the Ottomans used janissaries. He moved the capital to Isfahan and made it a showpiece: an enormous central square, a bazaar, a blue-tiled royal mosque and gardens. He welcomed Armenian Christian merchants, moving thousands of them to a suburb of the city, because they ran the silk trade with Europe and India that paid for his state.

Isfahan was so grand that Persians said it was half the world. English and Dutch trading companies opened offices there. Yet the Safavid state depended heavily on the shah himself. After Abbas, weaker rulers let the army decay and the treasury empty. In 1722 an army of Afghan rebels captured Isfahan and the dynasty collapsed. Its religious legacy outlasted its political one by centuries.

In 1526 Babur, a prince descended from both Genghis Khan and Timur, defeated the sultan of Delhi with cannon and muskets at Panipat. His grandson Akbar, who reigned from 1556 to 1605, turned the conquest into an empire. Akbar’s genius was organization. He divided the empire into provinces run by paid officials. He had every field measured and its usual yield recorded, then set a land tax at a fixed share of the crop, collected in cash. This land revenue system gave the Mughals a steady income far larger than any European king’s.

Akbar also built a system of ranks called mansabdars: every noble held a number that fixed his salary and how many cavalry he had to supply. Ranks were not inherited, and when a noble died his property returned to the emperor. This kept the nobility dependent and the army large. Hindu Rajput warriors were given high ranks and married into the royal family. Akbar abolished the jizya, the tax on non-Muslims, in 1564, and welcomed all faiths at court.

His descendants inherited great wealth. Shah Jahan, who reigned from 1628 to 1658, built the Taj Mahal at Agra as a tomb for his wife Mumtaz Mahal; it took more than twenty years and thousands of workers. Mughal India in the 1600s produced perhaps a quarter of the world’s manufactured goods, above all cotton cloth, and sold it to Asia, Africa and Europe. The Dutch and English East India Companies begged for permission to trade at Mughal ports.

Shah Jahan’s son Aurangzeb, who reigned from 1658 to 1707, spent decades at war in the south and reversed Akbar’s policy. He restored the jizya in 1679, destroyed some Hindu temples and enforced strict Islamic law. Whether this or the endless wars did more damage, historians argue. What is clear is that revolts by Marathas, Sikhs and Rajputs multiplied. After Aurangzeb’s death the empire fragmented, and by the 1740s the emperor in Delhi ruled little beyond the city.

The Ming dynasty had ruled China since 1368. By the early 1600s it was in trouble. Silver imports fell, taxes rose, harvests failed in a cold spell, and peasants rebelled. In 1644 a rebel army took Beijing and the last Ming emperor hanged himself. A Ming general then made a fateful choice: he opened the gate in the Great Wall to the Manchus, a people from the northeast, to help crush the rebels. The Manchus crushed them and stayed. Their dynasty, the Qing, ruled China until 1912.

The Manchus were a tiny minority ruling a vast population. They kept themselves separate, organized under military units called banners, and forbade intermarriage with Chinese. They ordered every Chinese man to shave his forehead and wear his hair in a long braid, the queue, as a sign of submission. But they also kept the Ming system almost intact: the civil service exams, the Confucian officials, the same ministries. Two great emperors, Kangxi and his grandson Qianlong, between them ruled for more than a century.

Under the Qing, China roughly doubled in size. Armies conquered Taiwan, Mongolia, Tibet and the far western region of Xinjiang. Population grew fast, from perhaps one hundred fifty million to more than three hundred million by 1800, fed partly by corn and sweet potatoes from the Americas. Kangxi welcomed Jesuit missionaries at court for their skill in astronomy, mapmaking and cannon casting, though few Chinese converted. Silver from the Americas kept flowing in to pay for tea, silk and porcelain.

The Qing were confident, and they had reason to be. In 1757 the court limited European traders to the single port of Canton, dealing through licensed Chinese merchants. It was not that China feared Europe; it was that China did not much need it. A British visitor in the 1790s would be told that the empire possessed all things and had no use for foreign manufactures. That confidence would look different a century later, but in 1750 it was hard to argue with.

In 1600, at the battle of Sekigahara, a warlord named Tokugawa Ieyasu defeated his rivals and ended more than a century of civil war among Japan’s feudal lords, the daimyo. In 1603 the emperor, who reigned but did not rule, named him shogun, supreme military commander. Ieyasu built his capital at Edo, the fishing village that became Tokyo. His family would hold the office of shogun for more than 250 years.

The Tokugawa kept the peace by controlling the daimyo. Each lord ruled his own domain but had to spend every other year in Edo and leave his wife and children there permanently when he went home. This system, called alternate attendance, kept the lords under the shogun’s eye, and the cost of keeping two households and traveling with a large escort drained their treasuries. Roads, inns and towns grew up along the routes. Edo became one of the largest cities in the world, with about a million people by the 1700s.

Foreigners were the other threat. Portuguese traders and Jesuit missionaries had arrived in the 1540s, bringing muskets and Christianity, and by 1600 there may have been three hundred thousand Japanese Christians. The shoguns feared that Christian daimyo might ally with European powers. They banned Christianity in 1614, executed missionaries and converts, and crushed a rebellion of Christian peasants in 1638. In the 1630s a series of edicts forbade Japanese to leave the country or return, and expelled almost all Europeans.

The policy is called sakoku, the closed country, though the door was never fully shut. Dutch traders were allowed one tiny artificial island in Nagasaki harbor, and Chinese and Korean merchants also traded under strict rules. Through that Dutch window, Japanese scholars studied European medicine, astronomy and guns in what they called Dutch learning. Japan enjoyed two centuries of peace, growing cities, printed books and popular theater. It also missed much of what was happening in the world, a gap it would have to close in a hurry after 1853.

In 1697 a very tall young man traveling under a false name turned up in a Dutch shipyard and asked for work as a carpenter. He was Peter, tsar of Russia, on a tour of Western Europe to learn how it built ships, cast cannon and ran governments. Russia was huge, mostly peasant, and cut off from Europe’s seas and ideas. Peter had decided to change that by force. He reigned from 1682 to 1725, and by the end no one could doubt he had.

He started with symbols. Returning home, he ordered nobles to shave their beards and wear Western clothes, and taxed those who refused. He moved the calendar and the alphabet closer to Europe’s. Then he built substance. He created a navy from nothing, founded schools of navigation and engineering, and replaced the old nobility of birth with a Table of Ranks in 1722 that tied noble status to service in the army or government. A commoner who rose through the ranks became a noble; a noble who did not serve lost his standing.

Peter’s obsession was a port on the Baltic Sea, which Sweden controlled. The Great Northern War lasted from 1700 to 1721. After early defeats, Peter rebuilt his army with muskets, drill and cannon cast from church bells, and crushed the Swedes at Poltava in 1709. On marshy land captured from Sweden he built a new capital, St. Petersburg, laid out on European lines with canals and palaces. Tens of thousands of forced laborers died building it. He called it his window on Europe.

The cost fell on ordinary Russians. Taxes rose steeply, and Peter tightened serfdom so that landlords could buy and sell peasants and the state could draft them for twenty-five years in the army. Russia became a great European power, but it did so by strengthening the two things that Western Europe was starting to weaken: the absolute power of the ruler and the bondage of the peasants. That contradiction would shape Russia for two hundred years.

Louis XIV became king of France in 1643, at four years old, and reigned for seventy-two years. As a boy he lived through a revolt of nobles that drove the royal family out of Paris. He never forgot it. When he took personal control of the government in 1661, he set out to make sure no noble, no parliament and no church could ever challenge the king again. The idea behind this was absolutism: the belief that a monarch holds complete power, answerable only to God.

Louis’s tools were money, officials and spectacle. His finance minister, Colbert, built up French industry, taxed trade and tried to keep gold inside the kingdom, a policy called mercantilism. Royal agents called intendants ran the provinces, bypassing local nobles. And Louis built Versailles, a palace outside Paris so vast that thousands of nobles lived there at his expense. Competing for the honor of handing the king his shirt in the morning, they had no time to plot rebellion. Louis called himself the Sun King: everything revolved around him.

Absolutism demanded one faith. In 1685 Louis revoked the Edict of Nantes, which had protected French Protestants for nearly a century. Hundreds of thousands of them, often skilled craftsmen and merchants, fled to England, the Netherlands, Prussia and America, taking their skills with them. Louis also spent most of his reign at war, expanding France’s borders and bankrupting its treasury. By his death in 1715 his army was the largest in Europe and his people were exhausted by taxes and famine.

Was absolutism as absolute as it claimed? Historians point out that Louis still had to bargain with provincial assemblies, sell government offices to raise cash, and tolerate tax exemptions for nobles and clergy. The king could not simply command; he had to persuade, reward and buy. But the model he set, of a ruler standing above all rivals and embodying the state, was copied by kings across Europe and challenged, within a century, by revolution.

England’s kings wanted what Louis had, and could not get it. Charles I, who came to the throne in 1625, tried to rule without Parliament, the assembly of nobles and elected gentry that by custom had to approve new taxes. He collected money by other means and ruled alone for eleven years. When he finally needed Parliament to pay for a war in 1640, its members demanded limits on his power instead. In 1642 the quarrel became a civil war between the king’s supporters and Parliament’s army.

Parliament won. In January 1649 Charles was tried for treason against his own people and beheaded in front of his palace. It was the first time a European monarch had been executed by a court in his subjects’ name. The general Oliver Cromwell ruled a republic for a decade, but it depended on the army and on him. When he died in 1658 no one could hold it together, and in 1660 Parliament invited Charles’s son back as Charles II. The question of who held final power was still open.

It was settled in 1688. James II, a Catholic, tried to override Parliament’s laws and appoint Catholics to office. When his wife bore a son who would be raised Catholic, leading nobles invited James’s Protestant daughter Mary and her Dutch husband William to invade. James fled without a battle. Because almost no blood was shed, the English called it the Glorious Revolution. William and Mary took the throne in 1689 on terms Parliament set.

Those terms were written into the English Bill of Rights of 1689. The monarch could not suspend laws, raise taxes or keep a standing army in peacetime without Parliament’s consent. Elections had to be free and parliamentary debate could not be punished. Subjects could petition the king, and cruel and unusual punishments were banned. It was not democracy; only a small fraction of men could vote. But it established that the ruler was under the law, and it gave English colonists in America a set of rights they would one day insist on.

Armies grew enormously between 1500 and 1750. A large European army in 1500 might number thirty thousand men. By 1700 France alone kept several hundred thousand under arms. Muskets, cannon, uniforms, fortresses and warships all cost money, and soldiers had to be paid or they mutinied. Historians call this the military revolution, and it forced rulers everywhere to become tax collectors on a scale the world had never seen.

States found money in different ways. The Ottomans and Mughals taxed land directly and paid many officials with the income of assigned districts. France used tax farming: it sold the right to collect a tax to private financiers, who paid the crown up front and then squeezed the taxpayers for a profit. Spain lived on American silver until it ran short, then borrowed from foreign bankers and defaulted repeatedly. Nobles and clergy in France and Spain were largely exempt, so the burden fell on peasants and townspeople.

The winners were the states that could borrow. In 1694 England created the Bank of England to lend to the government, and Parliament guaranteed the interest with specific taxes. Because lenders trusted that Parliament would pay, England could borrow huge sums at low rates. This national debt let a small country fight France for decades. The Dutch Republic had done the same earlier. A king who could not be trusted to repay, like Louis XIV or the kings of Spain, paid far more to borrow far less.

Money also shaped rights. Rulers who needed taxes had to bargain with those who paid them. Where assemblies like Parliament controlled the purse, they could trade money for limits on royal power. Where kings could tax without asking, as in France and Russia, assemblies withered. The connection between taxation and representation was not an American invention; it was the central struggle of the age, and the Americans inherited it.

If Newton could find the laws that governed the planets, could reason find the laws that should govern people? Thinkers across Europe in the 1700s believed it could. Historians call their movement the Enlightenment. Its center was France, its language was the printed pamphlet and the coffeehouse debate, and its targets were absolute monarchy, religious persecution and any claim that people should obey simply because they always had.

The English philosopher John Locke laid the foundation. Writing in 1690, just after the Glorious Revolution, he argued that all people are born with natural rights to life, liberty and property, and that governments exist to protect those rights. Rulers govern only with the consent of the governed. If a government attacks the rights it was created to protect, the people may replace it. Every phrase of that argument would reappear in the American Declaration of Independence in 1776.

French thinkers pushed further. Montesquieu, in 1748, studied governments from China to England and concluded that liberty survives only when power is divided: those who make laws, those who enforce them and those who judge should be separate branches that check each other. Voltaire attacked religious intolerance with wit and made a career of defending its victims. Rousseau argued in 1762 that a just government expresses the will of the people as a whole. Diderot’s Encyclopedia gathered the era’s knowledge into volumes that the French crown tried and failed to suppress.

The Enlightenment had blind spots and critics. Most of its thinkers were men who did not extend rights to women, and several defended slavery or wrote of non-Europeans with contempt; others, like the marquis de Condorcet, argued that rights had to include everyone. Some monarchs, like Frederick of Prussia and Catherine of Russia, admired the philosophers while keeping absolute power. Yet the ideas escaped their authors. Within a generation they would be used by revolutionaries in Philadelphia, Paris and Haiti.

Put the empires side by side and patterns appear. On religion, the Ottomans let Christians and Jews run their own communities. Akbar’s Mughals abolished the tax on non-Muslims and welcomed every faith at court, until Aurangzeb reversed it. Louis XIV expelled his Protestants. Tokugawa Japan executed Christians. Tolerance was not a matter of East or West; it was a choice each state made, usually because of who it needed and what it feared.

Trade shows a similar spread. The Mughals and Ottomans welcomed foreign merchants because they profited from them; Indian cotton and Persian silk flowed out, and silver flowed in. Louis’s France and the English tried to control trade for the state’s benefit through mercantilist rules. The Qing allowed European trade but confined it to Canton. Japan shut the door to a crack. The more a state depended on customs duties and merchants, the more open it tended to be.

Every one of these rulers built to impress. Shah Jahan’s Taj Mahal, Shah Abbas’s Isfahan, the Ottoman mosques of Istanbul, Louis’s Versailles, Peter’s St. Petersburg and the Qing palaces of Beijing were all statements in stone: this state is rich, ordered and eternal. Art followed power. Mughal painters recorded court life in miniatures; Ottoman calligraphers and tile makers decorated mosques; French playwrights and composers performed for the Sun King. Japan’s peace produced popular art for city dwellers instead: woodblock prints and kabuki theater.

Which choices made a state strong? Tolerance of useful minorities usually paid off, as the flight of French Protestants showed. Openness to trade brought silver and knowledge but also foreign pressure, as China and India would learn after 1750. Reliable taxes and honest borrowing mattered more than palaces. And a state that rested on one extraordinary ruler, as Safavid Persia and Mughal India did, was only as strong as the next ruler turned out to be.

In 1683 an Ottoman army besieged Vienna for the second time and was routed by a relief force led by the king of Poland. Over the next decades the Ottomans lost Hungary and their aura of invincibility. In 1722 Afghan rebels captured Isfahan and ended the Safavid dynasty. After Aurangzeb died in 1707, Mughal power drained away to regional governors and Maratha armies; in 1739 a Persian invader sacked Delhi and carried off the Peacock Throne. Three empires that had dominated the world in 1600 were shadows by 1750.

The causes overlapped. War was the first. Aurangzeb spent twenty-five years campaigning in the south and gained little but debt and enemies. The Ottomans fought Persia, Austria, Russia and Venice, often at once. Second was succession. None of these empires had a clear rule for who came next, so the death of a ruler often meant a war among his sons, and the winner inherited a divided state. Third was money. Tax income fell as provincial officials kept more for themselves, while European silver, once a blessing, drove inflation that ate soldiers’ pay.

Fourth, and hardest to see at the time, was the growing strength of rivals. European states, forced to compete with each other in a crowded continent, had built better cannon, disciplined infantry, navies and, above all, reliable credit. Their trading companies were armed corporations with their own soldiers. When Mughal power collapsed in Bengal, the English East India Company was there to fill it. In 1757 its small army defeated the region’s ruler at Plassey and began to govern Indian provinces directly.

Historians warn against reading the story backward. In 1750 China was still the world’s largest economy, the Ottomans still ruled a vast territory, and no one in Delhi or Istanbul imagined that a trading company from a small island would rule India. Decline was not destiny. But the pattern is worth studying, because it repeats: states that stop adapting their armies, their finances and their institutions are overtaken by those that keep changing, whatever their size.