Araguaia River

The Araguaia River (Portuguese: Rio Araguaia [ˈʁi.u aɾaˈɡwajjɐ], Karajá: ♂ Berohokỹ [beɾohoˈkə̃], ♀ Bèrakuhukỹ [bɛɾakuhuˈkə̃]) is one of the major rivers of Brazil, and a tributary of the Tocantins River.

The Araguaia River comes from Goiás-Mato Grosso south borders. From there it flows northeast to a junction with the Tocantins near the town of São João. Along its course, the river forms the border between the states of Goiás, Mato Grosso, Tocantins and Pará. Roughly in the middle of its course the Araguaia splits into a fork (with the western stream retaining the name Araguaia and the eastern one being called the Javaés River). These later reunite, forming the Ilha do Bananal, the world's largest river island. The vein of the Javaés forms a broad inland delta where it pours back into the main Araguaia, a 100,000 hectare expanse of igapós or flooded forest, blackwater river channels, and oxbow lakes called Cantão, protected by the Cantão State Park. It is one of the biologically richest areas of the eastern Amazon, with over 700 species of birds, nearly 300 species of fish, large populations of species such as the giant otter, the black caiman, the pirarucú, one of the world's largest freshwater fish, and the Araguaian river dolphin (or Araguaian boto), all occurring within a large area. A large portion of the Araguaia's course is navigable all year, but the river below the Cantão wetlands is interrupted by rapids. The middle and lower basin of the river is in the Xingu–Tocantins–Araguaia moist forests ecoregion. The combined watershed of Araguaia and Tocantins rivers (named the Araguaia Tocantins Basin) covers approximately 9.5% of Brazil's national territory. This area is an integral part of the Amazon biome; however, the Araguaia River is not a tributary of the Amazon. "Araguaia" means "River of the macaws" in the native Tupi language.

Its principal tributary is the Rio das Mortes, which rises in the Serra de São Jerônimo, near Cuiabá, Mato Grosso, and is navigable to Pará. Other important tributaries include the Bonito, Garcas, Tapirape and the Formoso or Cristalino on the west, and the Pitombas, Claro, Vermelho, Tucupa and Chavante on the east.

The Araguaia River basin has been inhabited for thousands of years by various indigenous ethnic groups, including the Karajá, Javaé, and Xavánte, who continue to reside along its banks, particularly around the Ilha do Bananal—the world's largest river island formed by the Araguaia splitting into two channels. European contact in the region began in the 17th century. The discovery of gold in the river's tributaries by explorer Bartolomeu Bueno da Silva in 1682 spurred initial colonial penetration and led to the establishment of settlements like Santa Anna (now the city of Goiás). The 18th and 19th centuries saw limited success in colonizing the river valley, but the area was heavily exploited by slave-hunting expeditions from São Paulo and Belém, displacing and reducing the indigenous population. It was explored in part by Henri Coudreau in 1897. The Karajá do Norte, for instance, were subjected to a "very violent process of population loss," declining to just 3–4% of their former size by the mid-20th century due to conflicts and displacement from colonization.

Flows through: Brazil.

River data from Wikidata (CC0); lengths normalised to a common unit.