There is an island in the Andaman Islands in the Bay of Bengal that is illegal, by Indian governmental decree, to approach. There are somewhere between 50-400 people living on North Sentinel Island, but any and all attempts by anthropologists/biologists/government people to establish a line of communication with its residents and learn the language and culture of the indigenous tribe have failed. When the Sentinelese shot a volley of arrows at them. This isn’t just a one or two time thing; it is a consistent occurrence. They really do not want to be bothered.
Legally, this is fascinating because it means that they have never been conquered or occupied and are therefore not technically speaking under the governmental control of anyone. They are, however, considered to be a de facto autonomous region of India.*