 The evidence to support this claim comes from the discovery of numerous geoglyphs dating from between 1 and 1250 AD and terra preta.Some 5 million people may have lived in the Amazon region in 1500, divided between dense coastal settlements, such as that at Marajó, and inland dwellers.By 1900, the population had fallen to 1 million and by the early 1980s, it was less than 200,000.