Before Spanish invaders conquered South America, sparse groups of nomadic people clustered around the Amazon River, leaving the surrounding rain forest pristine and untouched.

Or did they?

New research suggests a very different story—an Amazonian region peppered with rain forest villages, ceremonial earthworks, and a much larger population than previously thought.

The research, funded in part by the National Geographic Society and published today in the journal Nature Communications, challenges a common perception of the pre-Columbian Amazon rain forest as sparsely populated. That perception has endured despite 16th-century accounts of large, interconnected villages that go against modern assumptions.

“Many people have the image that it’s an untouched paradise,” says Jonas Gregorio de Souza, an archaeologist at the University of Exeter who collaborated