Archaeological evidence indicates that this region was inhabited over many centuries, but it seems likely that the modern population is mainly descended from various groups who took refuge in this watershed region from the seventeenth century onward. Their neighbors to the east, south, and west are other groups of mainly Carib-speaking Indians with whom the Trio intermarried, traded, and raided. To the north, from about the eighteenth century onward, contact was almost exclusively with the Bush Negroes, or Maroons, who inhabited the middle reaches of the Suriname River. This contact was of crucial importance to the Trio since trade with the Bush Negroes provided them with highly valued manufactured goods, above all metal-cutting tools. Although references to the Trio and various subgroups appear from the seventeenth century and contact was probable, the first recorded encounter was by Robert Schomburgk in 1843. Other contacts with the Trio during the nineteenth century were few, and it is not until the beginning of the twentieth century, with an increase in the number of expeditions into the region from both the Brazilian and Suriname sides, that the Trio received more frequent mention in the literature.
Until the late 1950s contact remained sporadic because there was no permanent White settlement in the region. Then, almost simultaneously on both sides of the frontier, airstrips were cut and permanently manned by a few non-Indians. From the Trio point of view the most important event that took place at that time was the arrival of two missionary organizations, a Franciscan mission in Brazil and a U.S. Protestant group in Suriname. The policies pursued by these two groups are very different. There is also a difference in civil status afforded to the Indians by the respective nations. In Suriname the Indian is a full citizen of the country with the right to vote and to pensions and welfare benefits, but the Indian's right to land is not guaranteed since all land is owned by the state. In Brazil the Indian is still a minor, but at the moment the Trio live in a park in which their right to land is guaranteed. In describing Trio culture, however, it is necessary to bear in mind that many features of their society and culture have been transformed since the the late 1950s by external influences. The word "traditional" as used in the following description refers to the period prior to then.