In 1519 the Aztec Empire ruled millions of people from its island capital, Tenochtitlan. In 1532 the Inca Empire stretched thousands of kilometres down the Andes. Within a single generation, both were gone.
Hernán Cortés landed on the coast of Mexico in 1519 with a few hundred men. Francisco Pizarro landed in Peru in 1532 with an even smaller force. Neither could have won alone — but both conquests permanently ended two of the largest states in the Americas and replaced them with Spanish colonial rule.
The scale of the change: This was not a border adjustment like Westphalia or Zuhab. Two entire imperial systems of government were destroyed and replaced by a completely different one, run from Spain. That is why this case study belongs firmly under political and territorial effects.
How the empires fell
Tenochtitlan falls, 1521
Cortés allied with the Tlaxcalans, enemies of the Aztecs who resented paying tribute to them. After a long siege, weakened by hunger and disease, Tenochtitlan surrendered in 1521 and the Aztec emperor Cuauhtémoc was captured.
Cajamarca and the fall of the Inca, 1532–33
Pizarro seized the Inca ruler Atahualpa at a meeting in Cajamarca, demanded a huge ransom in gold and silver, and then executed him anyway in 1533. Without their emperor, Inca resistance fractured.
Local allies made conquest possible
Both conquests depended on Indigenous allies who had their own reasons to turn against the ruling empire — this was not simply a small Spanish force beating a huge one alone.
Two capitals fell within a decade of each other, and both empires' own rivals helped bring them down.
Civil war helped Pizarro: The Inca Empire had just fought a bitter civil war between two brothers, Atahualpa and Huáscar, over the succession. Pizarro arrived at the exact moment the empire was divided and exhausted — a stroke of timing, not just tactics.
Political rule: the viceroyalties
Spain did not just defeat two empires — it built entirely new systems of government over them. These were called viceroyalties, each ruled by a viceroy appointed directly by the Spanish crown.
- Viceroyalty of New Spain (1535) — covered Mexico and Central America, built on the ruins of the Aztec Empire, with its capital built directly on top of Tenochtitlan
- Viceroyalty of Peru (1542) — covered most of Spanish South America, built on the former Inca Empire
- Direct crown control — unlike the loose, negotiated peace of Westphalia, Indigenous rulers were not left in charge of anything; all real power flowed from Madrid
A new capital on an old one: Mexico City was built directly on the ruins of Tenochtitlan, using stones from destroyed Aztec temples. It is a striking, literal example of one political order being physically replaced by another.
So the political and territorial effect was total: no treaty, no negotiated peace, no surviving ruling dynasty. This is the most extreme version of "political and territorial change" that this unit's framework will ask you to discuss.
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The single most devastating effect of the conquest was not the fighting itself. It was disease — and the deaths from disease dwarf the deaths from any battle in this unit.
The real killer was invisible: Europeans carried smallpox, measles and influenza — diseases the Indigenous population had never been exposed to and had no immunity against. Smallpox reached Tenochtitlan just before the final siege in 1520–21 and killed huge numbers of defenders, including a newly crowned Aztec emperor.
Historians debate the exact numbers, but most estimates agree that the Indigenous population of Mexico fell by somewhere close to 90% within a century of contact. This is what historians mean by the Great Dying — the largest demographic collapse of the Early Modern period, anywhere in the world.
| Region | Rough population before conquest | Approximate decline |
|---|---|---|
| Central Mexico | Estimates vary widely, commonly cited around 20–25 million (1519) | Fell to roughly 1–2 million by the early 1600s |
| Andes (former Inca lands) | Several million | Fell by well over half within a century |
Treat the numbers carefully: Pre-conquest population estimates are disputed and historians argue over them. In an essay, say "estimates suggest a decline of this scale" rather than quoting one number as certain fact — that is exactly the kind of historical caution examiners reward.
Forced labour: encomienda and mita
Disease was not the only demographic pressure. The Spanish also built new systems of forced labour to run their new colonies, and these systems killed people too.
Encomienda
- A grant giving a Spanish encomendero the right to demand labour and tribute from a named Indigenous community
- In theory it came with a duty to protect and Christianise that community
- In practice, abuse and overwork were common and rarely punished
Mita
- A rotating forced-labour draft, adapted by the Spanish from an existing Inca system of labour service
- Used above all to force Indigenous men to work the Potosí silver mines
- Brutal conditions underground, and men were often away from their farms for months, damaging entire communities
Labour systems fed the demographic collapse: The mita in particular is a clear cause-and-effect chain: silver demand caused forced labour, forced labour caused death and family separation, and that fed straight back into population decline. Effects in this unit link together, and this is a strong example.
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Political conquest and demographic collapse were only part of the story. The conquest also transformed the economy, religion and culture of the Americas — and it set off forced migration across an entire ocean.
The silver economy
Potosí and Zacatecas
Huge silver deposits were found at Potosí (in modern Bolivia, from 1545) and Zacatecas (in modern Mexico, from 1546). Potosí alone became the largest source of silver in the world.
Silver funded the Spanish state
A fifth of all silver mined — the quinto real — went straight to the Spanish crown, funding its wars in Europe, including many of the conflicts covered elsewhere in this unit.
A genuinely global trade
Silver crossed the Pacific on the Manila galleons to pay for Chinese silk and porcelain, linking the Americas, Europe and Asia in one trading system for the first time.
Andean and Mexican silver paid for Spain's European wars and reshaped world trade.
Inflation crosses the Atlantic: So much silver flooded into Europe that prices rose sharply across the sixteenth century, a trend historians call the Price Revolution. An economic effect in the Americas therefore reached all the way into European households.
Religious conversion and cultural change
Spanish rule came with an explicit religious mission: convert the Indigenous population to Catholicism, by persuasion or by force.
- Mass conversion — Franciscan, Dominican and Jesuit missionaries baptised huge numbers of Indigenous people, sometimes within a single generation
- Destruction of temples and texts — Aztec temples were pulled down and their stones reused for churches; Spanish priests burned Maya and Aztec painted books, destroying irreplaceable Indigenous knowledge
- Syncretism — rather than disappearing completely, Indigenous belief often blended with Catholic practice, producing new hybrid traditions that still exist today
Our Lady of Guadalupe: In 1531, a vision of the Virgin Mary was reported to an Indigenous convert, Juan Diego, at a site in Mexico already linked to an Aztec mother goddess. The resulting devotion to Our Lady of Guadalupe is one of the clearest examples of religious syncretism anywhere in the Americas.
Population movement: the Atlantic slave trade
As the Indigenous population collapsed, colonists needed a new source of labour, especially on plantations in the Caribbean and coastal lowlands where mining labour drafts did not apply.
Enslaved Africans are forced across the Atlantic: From the early sixteenth century onward, growing numbers of enslaved Africans were shipped across the Atlantic to the Spanish Americas — the beginning of a trade that would eventually force millions of people across the ocean over the following three centuries.
This is the conquest's clearest demographic effect through migration: the same catastrophe that emptied Indigenous communities directly caused a new, forced, transatlantic movement of people to replace their labour.