Parts of the Amazon previously thought to have been uninhabited were home to thriving populations of up to a million people from as early as 1250 AD, research shows.
Archaeologists have uncovered evidence there were up to 1,500 fortified villages in the rainforest away from major rivers - two-thirds of which are yet to be discovered.
By analysing charcoal remains and excavated pottery, researchers found a 1,100-mile (1,800km) stretch of southern Amazonia that was continuously occupied from 1250 until 1500 AD.
These thriving populations were then decimated by the arrival of European settlers and their diseases.
People had assumed ancient communities had preferred to live near these waterways, but the new evidence shows this was not the case.