I guess more accurately, Chagos as a culture is founded by slaves who worked the island and were freed. It was originally part of the Seychelles and then transferred to be considered part of Mauritius, and then sold to the British, and then leased to the Americans, but the Chagossian people have never really considered themselves part of Mauritius. Certainly more part of Mauritius than Britain, but still distinct as a culture, people, and language.
Hail, Caesar