The impact of the Spanish conquest
The Scale of Indigenous Depopulation
The most catastrophic consequence of the Spanish conquest was demographic. Before the Europeans arrived, the population of central Mexico is estimated by historians at somewhere between five and thirty million people — the wide range reflects the difficulty of calculating pre-contact populations. Within a century of contact, that population had collapsed by an estimated 50–90 per cent, primarily from epidemic disease. Smallpox arrived in 1520; subsequent waves of measles, typhus, influenza and other diseases, to which indigenous people had no immune resistance, killed millions. One estimate suggests the central Mexican population fell from approximately 25 million in 1519 to around one million by 1600 — though these figures are contested among historians.
The indigenous population of central Mexico fell by an estimated 50–90 per cent within a century of Spanish contact, primarily from epidemic disease. Because indigenous peoples had no prior exposure to European diseases such as smallpox, measles and typhus, their immune systems offered no resistance — a “virgin soil epidemic.”
The Treatment of Indigenous Peoples: Encomienda and Forced Labour
The Spanish organised indigenous labour through the encomienda system. Each Spanish settler (encomendero) was allocated a group of indigenous people from whom they could demand tribute and labour. In theory, the encomendero was obliged to protect and Christianise their workers. In practice, it was forced labour under threat of violence, and conditions on encomiendas — particularly on agricultural estates and in mines — were brutal.
Mining was especially deadly. The silver mines of Potosí (in modern Bolivia, opened 1545) and other sites across New Spain used the mita — a rotating forced labour draft in which indigenous communities were required to supply a proportion of their men to work in mines for fixed periods. Conditions in the silver mines were lethal: men worked in near-darkness, inhaling toxic mercury vapour used in silver processing, with minimal food and no safety equipment. Life expectancy for mine workers was drastically shortened. The silver that flowed out of Potosí to Spain came at an enormous cost in indigenous lives.
Bartolomé de las Casas was a Spanish priest who had himself held an encomienda in the Caribbean before undergoing a dramatic change of conscience around 1514. He spent the rest of his life campaigning for indigenous rights, writing vivid accounts of Spanish atrocities and petitioning the Spanish crown to reform the colonial system. His most influential work, the Brevísima relación de la destrucción de las Indias (A Brief Account of the Destruction of the Indies, 1542), was translated into multiple languages and used by Spain’s Protestant rivals as evidence of Spanish cruelty — contributing to the “Black Legend” of Spanish colonial brutality. Las Casas’s advocacy contributed to the New Laws of 1542, which attempted (with limited success) to restrict encomienda abuses. He remains a deeply contested figure: praised as an early human rights defender, criticised for suggesting that enslaved Africans could replace indigenous labour.
The Imposition of Christianity
Christianity was imposed on indigenous populations throughout New Spain. Spanish missionaries — particularly Franciscan, Dominican and Augustinian friars — established missions across Mexico, teaching Christian doctrine, baptising converts and destroying indigenous religious sites and objects. The Templo Mayor in Mexico City was demolished; its stones used to build the new cathedral. Most Aztec codices were burned by Bishop Juan de Zumárraga and other churchmen who viewed them as works of the devil. Temples were torn down and churches built in their place, often on the same foundations.
The cultural impact was enormous. Indigenous religious practices did not disappear but went underground or blended with Christianity to create syncretic forms of worship. The syncretism also reshaped the Americas culturally: Spanish language, Catholic religion, European agricultural practices and livestock (horses, cattle, pigs) all transformed indigenous societies within a generation.
Spanish missionaries destroyed most Aztec codices and demolished indigenous temples, building Christian churches on the same foundations. The Aztec Templo Mayor in Mexico City was demolished and its stones used to build the new Spanish cathedral.
The Columbian Exchange and European Impact
The conquest initiated the Columbian Exchange — a vast transfer of goods, crops, animals and diseases in both directions across the Atlantic. From the Americas to Europe came maize, potatoes, tomatoes, chilli peppers, cacao and tobacco. These crops transformed European and global diets. From Europe to the Americas came wheat, cattle, horses, sugar cane, diseases and enslaved Africans.
The most dramatic European economic consequence was the Price Revolution: a sustained period of inflation across Europe during the sixteenth century. Spanish silver from the Americas — particularly from Potosí — flooded into European circulation, increasing the money supply and driving up prices. Wages lagged behind prices, impoverishing workers and peasants. Historians debate how much of the Price Revolution was caused by American silver versus other factors, but the connection is well established. Spain itself was paradoxically weakened by its silver wealth: easy money reduced incentives for domestic industry, and by the late sixteenth century Spain was using silver to pay for imports rather than building its own manufacturing base.
The conquest opened new trade routes and created new commodities. Cacao (chocolate) was initially used as currency in the Aztec empire and was introduced to Europe in the sixteenth century; by the seventeenth century it had become a luxury drink across Europe. Tobacco, also from the Americas, transformed European social habits. Sugar, grown in the Caribbean with enslaved African labour (as indigenous populations collapsed), became one of the most profitable commodities of the early modern period. The Atlantic economy — linking Europe, Africa and the Americas in a triangular trade — was a direct consequence of the voyages that began with Columbus in 1492.