It is probable that the first contacts of the Karajá with "civilization" date to the end of the sixteenth century and the beginning of the seventeenth, when explorers began to arrive in the Araguaia-Tocantins Valley. They came from Sao Paulo by land or by the rivers of the Parnaíba Basin, looking for Indian slaves and gold. When gold was discovered in Goiás around 1725, miners from several regions headed there and founded villages in the region. It was against these men that the Indians had to fight to defend their territory, families, and freedom. A military post was established in 1774 to facilitate navigation. Karajá and Javaé lived on the post that was called the Nova Beira colony. Other colonies were founded later but none was successful. The Indians had to adapt to a new way of life and were subject to various contagious diseases to which they had no immunity and for which they had no treatment.
A new phase of colonization began in Goiás when the gold mines became exhausted toward the end of the eighteenth century. With Brazilian independence, the government became more interested in preserving the territorial unity of Goiás and restructuring the economy. In 1863 Couto de Magalhães governor of Goiás, descended the Rio Araguaia. He intended to develop steam navigation and to promote colonization of lands along the border of the river. New villages were founded as a result of this initiative, and steam navigation increased along the Araguaia. Only recently has the region been drawn into the national economy, however. The Service of Protection to the Indians (SPI) permitted cattle raisers to occupy the fields that border the river, gradually involving the Karajá, Javaé, Tapirapé, and Avá (Canoeiros) Indians and causing much change in their lives, as the Indian territories were invaded by the cattle herds during the rainy season. When the military government took power in 1964, the SPI ceased to exist, and the Fundação Nacional do Indio (National Indian Foundation, FUNAI) was created, with similar functions. Reports of writers, travelers, government workers, and ethnologists indicate accentuated depopulation among the Karajá from the seventeenth to the twentieth centuries.