Scientists uncover a lost Amazon civilization hidden beneath the rainforest using lasers, may have been home to 3 million people

Researchers have uncovered hundreds of previously unknown ancient earthworks hidden beneath the Amazon rainforest using LiDAR technology, revealing that the Aquiry civilization was far larger and more populous than previously believed. The discovery challenges the long-held belief that the Amazon was an untouched wilderness, suggesting instead that it was a landscape extensively shaped by large and complex human societies.

The Aquiry civilization flourished in southwestern Amazonia between around 600 BCE and 850 CE. During this period, its people carved vast geometric earthworks into the landscape, creating ceremonial and public spaces connected by straight roads.

As reported by Science Alert, to make the discovery, researchers used LiDAR (Light Detection and Ranging), a remote-sensing technology that fires laser pulses from aircraft to map the ground beneath dense forest canopies. The technique allowed scientists to detect ancient structures that had remained hidden for centuries.

Nearly 400 previously unknown earthworks discovered

Surveying about 4,497 square kilometers of rainforest in Brazil, the research team identified 432 earthworks, including 396 previously unknown sites.

Most of the newly discovered structures consist of ditches and embankments arranged in geometric shapes such as squares, rectangles and circles. One remarkable complex, known as D. Schaan, features a monumental nested rectangular earthwork along with several perfectly square enclosures linked by broad roads.

Although the exact purpose of these earthworks remains uncertain, researchers believe they served as ceremonial, political and public gathering centers where communities met for festivals, rituals, social events and decision-making.

Discovery may be just the beginning

Researchers believe the known sites represent only a small fraction of what remains hidden beneath the rainforest.

By extrapolating their findings across the entire 183,000-square-kilometer region once occupied by the Aquiry civilization, they estimate that 24,000 to 30,000 earthworks may exist. "More than 20,000 earthworks may exist within this region alone," Martti Pärssinen, Professor Emeritus at the University of Helsinki and an expert in South American archaeology, was quoted as saying by IFL Science.

The study estimates that at its peak, between 100 CE and 300 CE, the Aquiry civilization may have supported 1.2 to 3 million people, making it one of the largest known pre-Columbian societies in the Amazon.

Ancient Amazon was home to thriving societies

The findings add to growing evidence that the Amazon rainforest was not an empty wilderness before European contact but a region occupied by thriving and sophisticated civilizations.

"If future research produces similar results in other parts of Amazonia, many long-standing assumptions regarding the scale of past human influence on the Amazon rainforest and its biological and ecological structure may need to be fundamentally reassessed," Pärssinen said.

The Aquiry culture takes its name from the Indigenous word for the Acre River, which flows through Peru, Bolivia and Brazil's Acre state. The civilization consisted of interconnected communities linked by shared traditions rather than a single centralized state.

Although the Aquiry left no written records and their homes have disappeared, their massive earthworks remain. These monumental geometric enclosures, surrounded by deep ditches and connected by straight roads, are among the few surviving traces of their civilization.

Rainforest reclaimed the ancient landscape

After the civilization disappeared around 850 CE, the rainforest gradually reclaimed much of the landscape. While some earthworks became visible during modern land clearing, their true scale remained hidden until the use of LiDAR.

"What surprised us most was the extraordinarily large number of geoglyphs and other earthworks found within an area representing less than 3 percent of Greater Amazonia," Pärssinen said.

Based on the findings, researchers believe the civilization once occupied an area of approximately 183,000 square kilometers, supporting millions of people and containing tens of thousands of monumental earthworks.

Describing what the region may have looked like around 200 CE, Pärssinen told ScienceAlert: "At the center of many of these clearings would stand large geometric earthworks connected by broad and narrow roads." "At certain times of the year, these places would come alive with ceremonies, gatherings, music, dancing, athletic competitions, and other communal events."

Researchers say these settlements were likely surrounded by large wooden longhouses, with nearby fields growing maize, manioc, squash and cotton. The surrounding forests would also have contained carefully managed fruit- and nut-bearing trees, reflecting centuries of human stewardship.

Many questions remain unanswered, including why the civilization disappeared between 850 CE and 1000 CE. The study has been published in the journal Nature.