The Para River is a major tributary of the AMAZON River, located in northern Brazil. The Xingu River is a major tributary of the AMAZON River, located in the Brazilian state of Mato Grosso. The Parnaíba River is a major river in northeastern Brazil, and is the longest river entirely within the country. The ACRE River is a major tributary of the AMAZON River, located in western Brazil. The Pardo River is a major tributary of the AMAZON River, located in the Brazilian state of Mato Grosso. All of these rivers are important to the geography and culture of Brazil.