Flying lasers over some of the densest rainforest on Earth, archaeologists have found hundreds of ancient monumental earthworks hidden beneath the southwestern Amazon — evidence of a mysterious civilization that thrived around two thousand years ago.

The lidar survey revealed nearly 400 previously unknown geometric structures — ditches, walls and ceremonial enclosures — attributed to the Aquiry civilization and dating mostly to roughly C.E. 100–300. Many are geometric in form and appear to have served ceremonial purposes. The scale of the discovery is the striking part: previous mapping had identified a few dozen such sites; the new survey multiplies that number many times over in a single region near the Brazil–Bolivia–Peru border.

Because lidar can only see through the canopy where it has been flown, researchers estimate that tens of thousands of similar earthworks remain hidden across the Amazon basin. That points to a pre-Columbian population far larger and more organized than once assumed — some estimates suggest the culture grew to as many as 3 million people, reshaping ideas about how much of the 'pristine' Amazon was actually shaped by human hands.

The findings help redefine the Amazon's past: rather than an untouched wilderness, parts of it were a managed landscape of roads, earthworks and settlements. The study adds to a growing body of evidence that Indigenous peoples transformed vast regions of the rainforest long before European contact.

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