Reports of an ape-like bipedal mammal have been documented in the Central Highlands area of Vietnam all the way back to the beginning of the 19th century, when the region came under French control and was known as Indo-China, progressively explored by missionaries and adventurers. The actual first reference to these creatures in literature comes from 1820. Before US occupancy in the later 20th century, villagers of the central highlands had kept the French and other Vietnamese at bay, holding to their solitude and simple means of existence.