Uncontacted peoples are groups of indigenous peoples living without sustained contact with neighbouring communities and the world community. Groups who decide to remain uncontacted are referred to as indigenous peoples in voluntary isolation. Legal protections make estimating the total number of uncontacted peoples challenging, but estimates from the Inter-American Commission on Human Rights in the UN and the non-profit group Survival International point to between 100 and 200 uncontacted peoples numbering up to 10,000 individuals total. A majority of uncontacted peoples live in South America, particularly northern Brazil, where the Brazilian government and National Geographic estimate between 77 and 84 tribes reside.

Knowledge of uncontacted peoples comes mostly from encounters with neighbouring indigenous communities and aerial footage.

Instruction: What are Uncontacted peoples?
Response: Uncontacted peoples generally refers to indigenous peoples who have remained largely isolated to the present day, maintaining their traditional lifestyles and functioning mostly independently from any political or governmental entities. However, European exploration and colonization during the early modern period brought indigenous peoples worldwide into contact with colonial settlers and explorers. As such, most indigenous groups have had some form of contact with other peoples. The term "uncontacted" therefore refers to a lack of sustained contact with the majority of non-indigenous society at the present time.

The Inter-American Commission on Human Rights refers to uncontacted peoples as "indigenous peoples in voluntary isolation." These groups are defined by their general rejection of contact with anyone outside of their own people. This definition also includes groups who have previously had sustained contact with the majority non-indigenous society but have chosen to return to isolation and no longer maintain contact. As such uncontacted peoples are understood not as living in an anachronistic state of nature but rather as contemporaries of modernity.

A 2009 United Nations report also classified "peoples in initial contact" as sharing the same characteristics but beginning to regularly communicate with and integrate into mainstream society.

To highlight their agency in staying uncontacted or isolated, international organizations emphasize calling them "indigenous peoples in isolation" or "in voluntary isolation". Otherwise they have also been called "hidden peoples" or "uncontacted tribes".

Historically European colonial ideas of uncontacted peoples, and their colonial claims over them, were informed by the imagination of and search for Prester John, king of a wealthy Christian realm in isolation, as well as the Ten Lost Tribes of Israel, identifying uncontacted peoples as "lost tribes".

International organizations have highlighted the importance of protecting indigenous peoples' environment and lands, the importance of protecting them from exploitation or abuse, and the importance of no contact in order to prevent the spread of modern diseases.

Historic exploitation and abuse at the hands of the majority group have led many governments to give uncontacted people their lands and legal protection. Many indigenous groups live on national forests or protected grounds, such as the Vale do Javari in Brazil or the North Sentinel Island in India.

Much of the contention over uncontacted peoples has stemmed from governments' desire to extract natural resources. In the 1960s and 1970s, Brazil's federal government attempted to assimilate and integrate native groups living in the Amazon jungle in order to use their lands for farming. Their efforts were met with mixed success and criticism until, in 1987, Brazil created the Department of Isolated Indians inside of FUNAI (Fundação Nacional do Índio), Brazil's Indian Agency. FUNAI was successful in securing protected lands which have allowed certain groups to remain relatively uncontacted until the present day.

A different outcome occurred in Colombia when the Nukak tribe of indigenous people was contacted by an evangelical group. The tribe was receptive to trade and eventually moved in order to have closer contact with settlers. This led to an outbreak of respiratory infections, violent clashes with narco-traffickers, and the death of hundreds of the Nukak, more than half of the tribe. Eventually, the Colombian government forcibly relocated the tribe to a nearby town where they received food and government support but were reported as living in poverty.

The threats to the Nukak tribe are generally shared by all peoples in isolation, particularly the outside world's desire to exploit their lands. This can include lumbering, ranching and farming, land speculation, oil prospecting and mining, and poaching. For example, then Peruvian President Alan García claimed in 2007 that uncontacted groups were only a "fabrication of environmentalists bent on halting oil and gas exploration". As recently as 2016, a Chinese subsidiary mining company in Bolivia ignored signs that they were encroaching on uncontacted tribes, and attempted to cover it up. In addition to commercial pursuits, other people such as missionaries can inadvertently cause great damage.

It was those threats, combined with attacks on their tribe by illegal cocaine traffickers, that led a group of Acre Indians to make contact with a village in Brazil and subsequently with the federal government in 2014. This behaviour suggests that many tribes are aware of the outside world and choose not to make contact unless motivated by fear or self-interest. Satellite images suggest that some tribes intentionally migrate away from roads or logging operations in order to remain secluded.

Indigenous rights activists have often advocated that indigenous peoples in isolation be left alone, saying that contact will interfere with their right to self-determination as peoples. On the other hand, experience in Brazil suggests isolating peoples might want to have trading relationships and positive social connections with others, but choose isolation out of fear of conflict or exploitation. The Brazilian state organization National Indian Foundation (FUNAI) in collaboration with anthropological experts has chosen to make controlled initial contact with tribes. The organization operates 15 trading posts throughout protected territory where tribes can trade for metal tools and cooking instruments. The organization also steps in to prevent some conflicts and deliver vaccinations. However, FUNAI has been critical of political will in Brazil, reporting that it only received 15% of its requested budget in 2017. In 2018, after consensus among field agents, FUNAI released videos and images of several tribes under their protection. Although the decision was criticized, the director of the Isolated Indian department, Bruno Pereira, responded that "The more the public knows and the more debate around the issue, the greater the chance of protecting isolated Indians and their lands". He shared that the organization has been facing mounting political pressure to open up lands to commercial companies. He also justified the photography by explaining that FUNAI was investigating a possible massacre against the Flechieros tribe.

Recognizing the myriad problems with contact, the United Nations Human Rights Council in 2009 and the Inter-American Commission on Human Rights in 2013 introduced guidelines and recommendations that included a right to choose self-isolation.

There have been reports of human safaris in India's Andaman Islands and in Peru, where tourism companies attempt to help tourists see uncontacted or recently contacted peoples. This practice is controversial.