Languages may be grouped in many ways, but the major language groupings or families of South America may be conveniently divided into the Macro- In the 1500s, the central Andes, the area of greatest population density in South America (about 10 persons per square mile), was sparsely populated compared to centres of Old World civilization.
Yet its population of approximately 3,500,000, crowded into narrow coastal valleys and small highland basins on approximately 1 percent of Peru’s total land area, constituted a much higher density than could be found in any other part of South America.
The chiefdoms of the northern Andes, northern Venezuela, and the Antilles had an estimated total population of 1,900,000, with densities ranging from 6.6 to 1.1 persons per square mile (2.5 to 0.4 persons per square kilometre).
The southern Andes was inhabited by the Araucanians, whose combined population was possibly 1,131,000, with a density range of 0.38 to seven persons per square mile.
The archaeological record for the central Andes shows a step-by-step development of cultural and social forms from a preagricultural, hunting and gathering baseline some 10,000 years ago to the Inca empire in the 15th century .