Photo: uncontactedtribes.org.
In “Los Pueblos Indígenas en Aislamiento: Su lucha por la sobrevivencia y la libertad” (Indigenous Peoples in Isolation: Their struggle for survival and freedom) (2002), Beatriz Huertas Castillo explains that any term used to refer to these groups is necessarily artificial, since, precisely because of their lack of contact with mainstream society, there is no way of knowing how they refer to themselves. The terms used to refer to these groups of people in general include “uncontacted”, “isolated”, “in voluntary isolation” and “lost tribes”, among others, but they all refer to the same concept. Among international organizations, the most commonly used term is “indigenous peoples living in voluntary isolation”. But the adjective “voluntary” can also be controversial: although one could say that indigenous peoples living in isolation have chosen to remain isolated by their own free will, it should also be stressed that they have been forced into this “choice” by a long history of tragic contacts with the surrounding population.
Source: http://www.iwgia.org/iwgia_files_publications_files/0603_aislados_contacto_inicial.pdf