Before the beginning of European colonization of the New World in the 15th century, an estimated seven to ten million Amerindians lived in American rainforests, half of them in
Brazil. Great cities existed in the Andes, while the Amazon supported agricultural societies.
The arrival of Europeans brought about the end of the native civilizations in Central and South America. Europeans carried diseases that killed millions of Amerindians, and within 100 years of the arrival of these outsiders, the Amerindian population was reduced by 90 percent. Most of the surviving native people lived in the interior of the forest, either pushed there by the Europeans, or living traditionally in smaller groups.