The Andaman and Nicobar Islands, a union territory of India, are a group of more than five hundred rainforest islands in the Indian Ocean, closer to Bangkok than Calcutta. Some of the first settlers came to the islands in 1858 when the British Indian government built a penal colony to imprison the rebels of the Sepoy Mutiny; another wave arrived in 1947 after Partition. The indigenous people are the descendants of hunter-gatherers who came to the islands about 55,000 years ago. Only four tribes survive on the Andaman Islands, with populations numbered in the dozens or low hundreds. John Allen Chau, a 26-year-old American from Vancouver, Washington, went to North Sentinel Island last month.