Expansion of Empires

For centuries, the Silk Road carried goods, ideas, and disease across Eurasia by land. Then, in 1453, the Ottomans took Constantinople, and Europe's overland route to the riches of Asia closed. What happened next reshaped the entire planet. Welcome to Unit 4.

Header landmark: Padrão dos Descobrimentos (Monument to the Discoveries) — Lisbon

No single European invention made transatlantic sailing possible. Instead, sailors combined a Chinese compass, a Chinese rudder, an Arab sail, and a Greek instrument refined in the Middle East. The ships that crossed the Atlantic were themselves proof of global exchange before a single voyage began.

Header landmark: Belém Tower — Lisbon

A small, poor kingdom with excellent harbors and a prince obsessed with maps built the first European trade empire along the coast of Africa, decades before Columbus ever set sail. Every later voyage of exploration followed a path Portugal cleared first.

Header landmark: Fortress of Sagres — Cape St. Vincent, Portugal

Christopher Columbus never found the route to Asia he promised Spain's monarchs. What he found instead reshaped the world so completely that historians still argue over how to remember him.

Header landmark: Monastery of La Rábida — Palos de la Frontera, Spain

Two nations drew a single line through the Atlantic Ocean and claimed everything on either side belonged to them. Cartographers had to make sense of a rapidly expanding world, one negotiated line at a time.

Header landmark: Casas del Tratado — Tordesillas, Spain

Spain and Portugal had a decades-long head start, but France, England, and the Netherlands were not willing to be left out. Watching Spanish silver and Portuguese trade goods flow home, they set out to build empires of their own.

Header landmark: Place Royale and Champlain's Habitation — Quebec City

On a cluster of islands in a shallow lake, refugees who had once served as mercenaries built one of the largest cities on Earth. By 1502, the Aztec emperor Moctezuma II ruled an empire of thirty-eight provinces from the temples of Tenochtitlán.

Header landmark: Templo Mayor ruins — Mexico City

No wheels, no writing system, and some of the most difficult terrain on Earth. Despite all of this, the Inca built an empire of twenty-five thousand miles of roads stretching from modern Colombia to Chile, tied together by a recordkeeping system made entirely of knotted string.

Header landmark: Machu Picchu — Peru

Long before the Aztec or Inca Empires rose to power, the Maya built forty rival city-states across Central America, developed one of the most accurate calendar systems in the ancient world, and independently invented the concept of zero.

Header landmark: Temple I at Tikal — Guatemala

Hernán Cortés arrived in Mexico with a few hundred men. He left as the conqueror of an empire of millions, aided as much by disease and Indigenous allies as by Spanish weapons.

Header landmark: Plaza of the Three Cultures (Tlatelolco), site of the 1521 surrender — Mexico City

Francisco Pizarro conquered an empire of millions with a few hundred soldiers, but he did not do it alone. A smallpox epidemic and a civil war over succession had already left the Inca Empire dangerously divided before he ever arrived.

Header landmark: Ransom Room (Cuarto del Rescate) — Cajamarca, Peru

Conquest did not end with a single battle. Across the Americas, Indigenous peoples faced a new system of forced labor called the encomienda, and responded in ways ranging from armed resistance to strategic adaptation.

Header landmark: Cerro Rico silver mountain — Potosí, Bolivia

Columbus described the people of Hispaniola as gentle and easily subjugated. Fifty years later, a former encomendero turned Dominican friar called the Spanish ravening wolves. Same islands, two radically different accounts.

Header landmark: Cathedral of Santo Domingo — Dominican Republic (first cathedral in the Americas)

Tomatoes were unknown in Italy. Horses were unknown in the Americas. Smallpox was unknown to Indigenous immune systems. In a single generation, contact between two hemispheres rewired agriculture, diet, and disease across the entire planet.

Header landmark: Archivo General de Indias — Seville

According to mercantilist theory, the world's wealth was a fixed pie. Every nation that got richer meant a rival got poorer. That single belief drove kings to found colonies, ban imports, and build the economic system that powered the entire Atlantic World.

Header landmark: Torre del Oro on the Guadalquivir — Seville (treasure-fleet port)

Not everyone believed mercantilism made sense. Two Scottish thinkers argued that trade did not have to be a competition where one side wins and the other loses, an idea that would eventually reshape the global economy.

Header landmark: Panmure House (Adam Smith's home) — Edinburgh

For centuries, West African trade flowed north across the Sahara. When Portuguese ships began arriving on the coast, and when the great empires of Songhai and Kanem-Bornu began to weaken, that trade quietly turned toward the Atlantic instead.

Header landmark: Elmina Castle — Ghana

European colonists first tried to force Indigenous peoples, then European indentured servants, to labor on American plantations. Both attempts failed, at horrific human cost. What followed was a system that would forcibly transport twelve million people across an ocean.

Header landmark: House of Slaves and its 'Door of No Return' — Gorée Island, Senegal

Rum for captives. Captives for sugar. Sugar for rum. The triangular trade linked three continents in a single, self-perpetuating cycle, and every leg of the triangle depended on enslaved human beings.

Header landmark: International Slavery Museum, Royal Albert Dock — Liverpool

Chained side by side with only inches of space above them, given food and water once a day, and held below deck for weeks at a time. As many as one in five people did not survive the Middle Passage. Those who did carried its memory for the rest of their lives.

Header landmark: Door of No Return memorial arch — Ouidah, Benin

Slavery existed in Africa long before Europeans arrived, but it was not the same institution that took hold in the Americas. Understanding the difference reveals exactly how the Transatlantic Slave Trade transformed an old practice into something new and far more brutal.

Header landmark: Cabins at McLeod Plantation Historic Site — Charleston, SC

Sugar was the most profitable crop grown by enslaved labor, and also the most physically brutal. Understanding how a plantation actually operated reveals the economic engine that drove the Transatlantic Slave Trade forward for centuries.

Header landmark: Morgan Lewis sugar windmill — Barbados

Not everyone who crossed the Atlantic in chains was enslaved for life, and not everyone who came voluntarily arrived free of coercion. The line between different forms of forced and unfree labor in the Atlantic World was often blurrier than it first appears.

Header landmark: Historic Jamestowne — Virginia

A Spanish conquistador, an Aztec survivor, an enslaved African, and an economist each experienced the birth of the Atlantic World differently. Today, you gather their perspectives and use them as evidence to make your own claim.

Header landmark: National Museum of African American History and Culture — Washington, D.C.

Twenty-four lessons ago, a closed trade route sent Europe looking west. Empires fell, continents exchanged crops and diseases, and twelve million people were forced across an ocean in chains. Now it is time to answer the question this entire unit has been building toward.

Header landmark: The Ark of Return memorial — United Nations, New York