The Sentinelese, or eponymously the North Sentinel Islanders, are a tribe who live on the North Sentinel Island — a part of the Andaman Islands. The catch? They refuse any contact with the outside world and react violently to those who do so. They were first peacefully contacted by Indian anthropologists in 1991 and there haven't been any other such instances since 1997.
The Sentinelese are hunter-gatherers and do not practice agriculture. They wear bark strings and necklaces, use canoes, and live in temporary huts. However, nothing is known about their language yet.