From the time of Christopher Columbus in Hispaniola, the conquerors of the New World made use of the encomienda system to profit from the peoples and territories they encountered. This system was a legacy of the methods used to reward military leaders in the time of the reconquista, when victorious officers received feudal privileges over conquered areas in return for their service. First in the Caribbean and then on the mainland, conquistadors granted their followers the right to employ groups of Native Americans as laborers and to demand tribute payments from them in exchange for providing food, shelter, and instruction in the Christian faith. Commonly, an individual conquistador was assigned a tribal chieftain along with all the people belonging to his kin group. This system was first used in Hispaniola to work goldfields and then in Mexico for agricultural labor and, when silver was discovered in the 1540s, for silver mining.

A 1512 Spanish law authorizing the use of the encomienda called for indigenous people to be treated fairly, but in practice the system led to terrible abuses, including overwork, beatings, and sexual violence. Spanish missionaries publicized these abuses, leading to debates in Spain about the nature and proper treatment of indigenous people (see “European Debates about Indigenous Peoples”). King Charles V responded to such complaints in 1542 with the New Laws, which set limits on the authority of encomienda holders, including their ability to transmit their privileges to heirs.

The New Laws provoked a revolt among elites in Peru and were little enforced throughout Spanish territories. Nonetheless, the Crown gradually gained control over encomiendas in central areas of the empire and required indigenous people to pay tributes in cash, rather than in labor. To respond to a shortage of indigenous workers, royal officials established a new government-run system of forced labor, called repartimiento in New Spain and mita in Peru. Administrators assigned a certain percentage of the inhabitants of native communities to labor for a set period each year in public works, mining, agriculture, and other tasks. Laborers received modest wages, which they could use to fulfill tribute obligations. In the seventeenth century, as land became a more important source of wealth than labor, elite settlers purchased haciendas, enormous tracts of farmland worked by dependent indigenous laborers and slaves.

Spanish systems for exploiting the labor of indigenous peoples were both a cause of and a response to the disastrous decline in the numbers of such peoples that began soon after the arrival of Europeans. Some indigenous people died as a direct result of the violence of conquest and the disruption of agriculture and trade caused by warfare. The most important cause of death, however, was infectious disease. Having little or no resistance to diseases brought from the Old World, the inhabitants of the New World fell victim to smallpox, typhus, influenza, and other illnesses. Overwork and exhaustion reduced indigenous people's ability to survive infectious disease. Moreover, labor obligations diverted local people from tending to their own crops, leading to malnutrition, starvation, and low fertility rates. Labor obligations also separated nursing mothers from their babies, resulting in high infant mortality rates.

The pattern of devastating disease and population loss established in the Spanish colonies was repeated everywhere Europeans settled. Overall, population declined by as much as 90 percent or more but with important regional variations. In general, densely populated urban centers were worse hit than rural areas, and tropical, low-lying regions suffered more than cooler, higher-altitude ones. Some scholars have claimed that losses may have been overreported, since many indigenous people fled their communities — or listed themselves as mixed race (and thus immune from forced labor) — to escape Spanish exploitation. By the mid-seventeenth century the worst losses had occurred and a slight recovery began.

Colonial administrators responded to native population decline by forcibly combining dwindling indigenous communities into new settlements and imposing the rigors of the encomienda and the repartimiento. By the end of the sixteenth century the search for fresh sources of labor had given birth to the new tragedy of the Atlantic slave trade (see “The Transatlantic Slave Trade” in Chapter 20).