The Chagossians are an Indo-African ethnic group originating from French slaves brought to the Chagos Islands, specifically Diego Garcia, Peros Banhos, and the Salomon island chain, in the late 18th century. Under international law, they are the indigenous people of the Chagos archipelago. Most Chagossians now live in Mauritius and the United Kingdom after being forcibly removed by the British government in the late 1960s and early 1970s so that Diego Garcia, the island where most Chagossians lived, could serve as the location for a United States military base. Today, no Chagossians are allowed to live on the island of Diego Garcia or anywhere in the Chagos archipelago, despite many of the islands they used to inhabit being over 160 km away from Diego Garcia.

The Chagos Archipelago or Chagos Islands is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives archipelago. This chain of islands is the southernmost archipelago of the Chagos–Laccadive Ridge, a long submarine mountain range in the Indian Ocean. In its north are the Salomon Islands, Nelsons Island and Peros Banhos; towards its south-west are the Three Brothers, Eagle Islands, Egmont Islands and Danger Island; southeast of these is Diego Garcia, by far the largest island. All are low-lying atolls, save for a few extremely small instances, set around lagoons.