In 2013, it was estimated that there were more than 100 uncontacted tribes around the world, mostly in the densely forested areas of South America, Central Africa, and New Guinea. Knowledge of the existence of these groups comes mostly from infrequent and sometimes violent encounters with neighbouring tribes, and from aerial footage.
Notable historical examples of encounters with previously uncontacted people are those between the Spanish Empire and the Arawak (and ultimately all of the Americas) in 1492; and the Aboriginal Australians with Europeans in 1788 when the First Fleet arrived in Sydney.
Uncontacted tribes are a source of fascination in "contacted" society, and the idea of tour operators offering extreme adventure tours to specifically search out uncontacted people has become controversial. A BBC Four documentary in 2006 documented a controversial American tour operator who specialized in escorted tours to "discover" uncontacted people in West Papua. In 1971 the BBC made a documentary, A Blank on the Map, hosted by Sir David Attenborough, in which the first contact was made with the Biami people of Papua New Guinea.
The Sentinelese continue to actively and violently reject contact. They live on North Sentinel Island, a small and remote island which lies to the west of the southern part of South Andaman Island in the Bay of Bengal. Their language is markedly different from even the other languages on the Andamans, which suggests that they have remained uncontacted for thousands of years. They have been called by experts the most isolated people in the world, and they are likely to remain so.