More than 20,000 ancient earthworks hidden beneath the Amazon rainforest have been revealed by airborne laser surveys, exposing the scale of a pre-colonial civilisation that sprawled across southwestern Amazonia far beyond what anyone had mapped before.

The study, published in the journal Nature on 6 August 2026, surveyed more than 4,400 km of flight over the Brazilian states of Acre and Amazonas using LiDAR — laser pulses fired from aircraft that penetrate the forest canopy to map the ground beneath. Of 432 earthworks definitively attributed to the civilisation in the study, only 36 had been previously recorded (The Art Newspaper).

The civilisation, named the Aquiry, flourished from around 600 BC until AD 850 and spanned roughly 183,000 sq km across modern-day Brazil, Bolivia and Peru. That footprint is about three times larger than researchers had previously estimated for the region's geoglyph-building societies. The researchers predict the area holds between 24,000 and 30,000 earthworks and other monumental landscape features in total, with roughly two-thirds belonging to the Aquiry.

The Aquiry built massive geometric earthworks: deep ditches paired with high embankments, some linked by roads. They lived in multifamily longhouses, farmed maize and squash, and managed useful Amazonian tree species including the Brazil nut tree, peach palm and uricuri palm. The earthworks served as sites for ceremonies, political gatherings and community bonding.

At its peak, between AD 100 and AD 300, the area may have supported between 1.25 million and 3 million people. The sites were abandoned between AD 850 and AD 950; the study does not establish a single cause.

The discovery's origins are modest. Professor Alceu Ranzi of the Federal University of Acre in Rio Branco, Brazil, had spotted geometric shapes from a commercial flight and invited Martti Pärssinen of the Instituto Iberoamericano de Finlandia in Madrid to Acre to see them. Pärssinen is one of the authors of the Nature paper, titled "Over 20,000 precolonial earthworks in the Southwest Amazonia" (Nature).

What makes this stand out is how much of this world was hiding in plain sight. A civilisation of millions, building monumental earthworks across an area larger than England, left a footprint so thoroughly swallowed by rainforest that two centuries of exploration found fewer than one in twelve of its known sites. The LiDAR flights did in a few seasons what walking the ground could not have done in generations.