With regard to factors such as geographical distribution, languages spoken and social organization, the 22 ethnic groups of the region of the Northwest Amazon can be divided into four groups, which are dealt with in different sections of the encyclopedia:

1) Ethnic groups of the Uaupés River: are distributed throughout this river basin and other basins to the south. Most speak languages of the Eastern Tukanoan family. They are organized into patrilineal, exogamic phratries and sibs (groups of desendants of a common ancestor who do not intermarry): Arapaso, Bará, Barasana, Desana, Karapanã, Kubeo, Makuna, Miriti-tapuya, Pirá-tapuya, Siriano, Tariana, Tukano, Tuyuka, Kotiria, Taiwano, Tatuyo, Yuruti (the last three listed are only found in Colombia).

2) Maku ethnic groups: These are located predominantly in the interfluvial regions along a line that runs in a general northwest-southeast direction, from the Guaviare River, in Colombia, to the Japurá, in Brazil, cutting through the Uaupés basin. They are organized in domestic groups (close kin of the husband and/or wife) and regional groups (agglomeration of neighboring villages), which speak dialects of the Maku language family: Dow, Hupda, Nadöb, Yuhupde, Kakwa, Nukak (the last two mentioned only live in Colombia).

3) Ethnic groups of the Içana and its tributaries the Cuiari, Aiari and Cubate. Speakers of Northern Arawakan languages: Baniwa and Kuripako.. They are organized into patrilineal, exogamic sibs and phratries.

4) Ethnic groups of the Xié River and Upper Rio Negro: They inhabit the borderland region between Brazil, Venezuela and Colômbia. The majority speak Língua Geral, or nheengatu, introduced by the first missionaries, in the XVIIIth Century: Baré and Warekena [or Werekena].