It was over twenty years ago when locals in Bolivia’s northern plains told archaeologist Heiko Prümers, with the German Archaeological Institute in Bonn, about mysterious mounds of earth in the nearby Amazon that showed signs of a hidden El Dorado. Surrounded by trees and covered in vegetation, it was hard to see what the mounds were exactly, but they caught Prümers’ interest. In 1999, he began excavating the site with a team of researchers, completely unaware of the massive discovery they were about to make.
What they uncovered were the remains of a vast and dense network of pre-Colombian settlements spanning more than 4,500 square kilometers (1,737 square miles) in Bolivia’s Llanos de Mojos region. The findings, published in Nature magazine in May, are the latest proof that large, complex urban societies existed in the Amazon before the arrival of the Spanish, challenging the idea that the rainforest was always a pristine, untouched wilderness.
Some experts say the urban area, which was home to thousands of Indigenous people from the Casarabe culture for nearly 900 years, is an example of how cities could exist in the rainforest without degrading the environment. Settlements did not contribute to forest loss and included a sophisticated agriculture and water management system, with hundreds of kilometers of canals and causeways to distribute water to crops and reservoirs.
Though, Prümers himself is skeptical that there is something more “ecological” about the Casarabe way of life compared to other cultures as the root of the settlements’ abandonment is still unknown. However, he says it’s clear they were dependent on their environment and their ability to use the resources around them to adapt to changing weather patterns.
For almost a millennia, the population built and inhabited a complex urban environment consisting of terraces, fortification walls, pyramids and causeways in the Amazonian savannah, during intense periods of heavy rains and droughts.
“It’s a very interesting because [the settlements are] very connected with ecological factors, in regions that are so dependent on small differences in rain that can have devastating consequences,” Prümers told Mongabay from his home in Germany, adding, “there’s still a lot of [archaeological] work to be done in the future.”