Until the conquistadors arrived from Spain, wiping out many tribes in the process, experts thought the Amazon was largely untouched. The region was only hospitable to small communities of nomadic hunter-gatherers because of the soil’s poor quality. But Heiko Prümers at the Deutsches Archäologisches Institut in Berlin and colleagues used Light Detection and Ranging (Lidar) technology to reconstruct a vast and complex urban society – originally lost to time – in the Llanos de Mojos region of the Bolivian Amazon. They found that the Casarabe society built complex and vast structures between A.D. 500-1400. The society decorated their cities in the annually flooded savannah with tall ceremonial structures, moats and interconnected roads and checkpoints.
"1491" is an excellent book on this subject. Charles C. Mann, published in 2006. Consolidates finds of all the disparate disciplines and covers from Bering Strait to Patagonia. Detailed, long, but not to be put down.