The Amazon rainforest has been home to many civilizations.
Archaeologists still have proof of this with the discovery of new sites in Bolivia.
Aerial images have revealed traces of these places buried under vegetation in an area of up to 4,500 km².
In total, 26 sites have been identified according to a study published in
Nature
and relayed by BFM TV.
Half were previously unknown to archaeologists.
"Our results put an end to arguments that the western Amazon was sparsely populated in pre-Hispanic times" and they provide new evidence that the Casarabe culture had a "highly integrated, continuous and dense settlement system", writes the archaeologist Heiko Prümers of the German Archaeological Institute.
Major, better-known sites
The Casarabe civilization populated the Amazon rainforest several thousand years ago.
But the importance of this population still remained unknown.
This study provides further information and highlights two large colonies: Cotoca and Landivar.
They dominated a regional network of sites which communicated by causeways which remain visible on the images, in spite of the abundant vegetation.
These two large sites had already been identified by the researchers, but "their massive size and architectural elaboration only became apparent through LIDAR (a distance measurement technique that uses the properties of light) survey", points out the study.
The Casarabe civilization moved several thousand cubic meters of earth to develop the Cotoca site.
Over time, it also built ramparts to defend itself and developed systems to control the irrigation water for crops.
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