North Sentinel Island, also known as “the illegal island,” is one of the Andaman Islands, located in the Indian Ocean, states Times of India. The indigenous people who live on the island, called the Sentinelese, have lived and been a tribe on the island for over 55,000 years, states Survival International.

The reason that the island is called “the illegal island” is because, in 1956, visiting the island was banned by the Indian government, explains The Premier Daily. The Culture Trip says that the island is banned because of diseases the Sentinelese could contract from visitors, since their immune system is not adapted for modern diseases. According to the source, the island is also illegal because of the dangers posed to outsiders. The Sentinelese attack anyone that visits their land. In 2004, a tsunami hit the island. A helicopter hovered over the island to provide the Sentinelese with food and supplies, though the Sentinelese did not appreciate the gesture, and continuously attacked the helicopter with arrows, states NDTV.

ED Tdtimes states that the reason the Sentinelese are so violent is because of a man named Maurice Vidal Portman. Many years ago, Portman would kidnap tribespeople and force them to pose in disturbing ways. Since then, the tribe has been violent to visitors, with an exception of an anonymous Indian Anthropological Survey director, who visited in 1991 and left without harm, explains Young Pioneer Tours. The government of India states the island should be left alone to protect the Sentinelese and preserve their land.

Many mysteries lie beneath North Sentinel Island. There are many questions about the Sentinelese and the origins behind the Island. Unfortunately, researchers believe these mysteries are unanswered and will remain as such for some time.