Amazon river dolphin widespread river dolphins. They are present in six countries in South America: Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, in an area covering about . The boundaries are set by waterfalls, such as the Xingu and Tapajós rivers in Brazil, as well as very shallow water. A series of rapids and waterfalls in the Madeira River have isolated one population, recognized as the subspecies "I. g. boliviensis", in the southern part of the Amazon basin in Bolivia. They are also distributed in the basin of the Orinoco River, except the Caroni River and the upper Caura River in Venezuela. The
Xingu peoples number had been reduced by foreign epidemic diseases such as flu, measles, smallpox and malaria to less than 1,000. Only an estimated 500 Xingu peoples were alive in the 1950s. The Brazilian Villas-Bôas brothers visited the area beginning in 1946, and pushed for the creation of the Parque Indígena do Xingu, eventually established in 1961. Their story is told in a film, "Xingu". The number of Xingu living there in 32 settlements has risen again to over 3000 inhabitants, half of them younger than 15 years. The Xingu living in this region have similar habits and social systems, despite different