<P> Since, the concept and definitions of Latin American are very modern, going back only to the nineteenth century, it is anachronistic to talk about "a history of Latin America" before the arrival of the Europeans . Nevertheless, the many and varied cultures that did exist in the pre-Columbian period had a strong and direct influence on the societies that emerged as a result of the conquest, and therefore, they cannot be overlooked . They are introduced in the next section . </P> <P> What is now Latin America has been populated for several millennia, possibly for as long as 30,000 years . There are many models of migration to the New World . Precise dating of many of the early civilizations is difficult because there are few text sources . However, highly developed civilizations flourished at various times and places, such as in the Andes and Mesoamerica . </P> <P> Christopher Columbus landed in the Americas in 1492 . Subsequently, the major sea powers in Europe sent expeditions to the New World to build trade networks and colonies and to convert the native peoples to Christianity . Spain concentrated on building its empire on the central and southern parts of the Americas allotted to it by the Treaty of Tordesillas, because of presence of large, settled societies like the Aztec, the Inca, the Maya and the Muisca, whose human and material resources it could exploit, and large concentrations of silver and gold . The Portuguese built their empire in Brazil, which fell in their sphere of influence owing to the Treaty of Tordesillas, by developing the land for sugar production since there was a lack of a large, complex society or mineral resources . </P> <P> During the European colonization of the western hemisphere, most of the native population died, mainly by disease . In what has come to be known as the Columbian exchange, diseases such as smallpox and measles decimated populations with no immunity . The size of the indigenous populations has been studied in the modern era by historians, but Dominican friar Bartolomé de las Casas raised the alarm in the earliest days of Spanish settlement in the Caribbean in his A Short Account of the Destruction of the Indies . </P>

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