The Amazon rainforest may have been home to one of the largest and most complex ancient societies in the Americas, according to new research that has uncovered hundreds of previously unknown archaeological sites concealed beneath dense forest.
Using airborne LiDAR technology, an international team of researchers identified nearly 400 previously undocumented earthworks in Brazil’s southwestern Amazon. Based on those discoveries, the team estimates that the wider region could contain more than 20,000 similar structures, dramatically expanding the known scale of human occupation in the area.
Laser Mapping Reveals a Vast Network
LiDAR, which uses laser pulses fired from aircraft to map the ground beneath vegetation, allowed researchers to detect geometric earthworks that have remained hidden under thick rainforest canopy for centuries.
The newly identified sites include large ditches, embankments and geometric enclosures arranged in circles, squares and rectangles. Many are connected by broad roads, suggesting they formed part of an extensive, carefully planned landscape rather than isolated settlements.
One particularly complex site features nested rectangular earthworks linked to multiple square enclosures, highlighting a level of engineering and planning that researchers say was previously unknown for the region.
Evidence of a Large Ancient Population
The study focuses on the pre-Columbian Aquiry civilization, which occupied parts of southwestern Amazonia between roughly 600 BCE and 850 CE.
Researchers estimate that the civilization may have supported between 1.25 million and 3 million people at its peak. If further investigations uncover similar evidence elsewhere in the Amazon Basin, it would reinforce the idea that the rainforest once supported far larger populations than historians traditionally believed.
Rethinking the Amazon’s Past
For decades, large sections of the Amazon were widely viewed as largely untouched wilderness before European colonization. The latest findings add to a growing body of archaeological evidence indicating that many parts of the rainforest were extensively managed by sophisticated Indigenous societies.
Researchers believe the earthworks likely served ceremonial, political and communal purposes, while surrounding areas were modified for agriculture, transportation and settlement. After these societies declined, the rainforest gradually reclaimed the landscape, concealing much of the evidence beneath dense vegetation.
Why the Discovery Matters
The findings could reshape scientific understanding of both Amazonian history and the relationship between ancient societies and tropical forests. Rather than existing in opposition to the rainforest, researchers suggest these communities actively shaped and managed their environment over centuries.
The study also demonstrates the growing importance of LiDAR technology in archaeology, allowing scientists to detect hidden landscapes without disturbing fragile ecosystems. Similar surveys have previously transformed understanding of ancient civilizations in Central America and Southeast Asia, and researchers believe much of the Amazon still remains unexplored.
What Comes Next
The authors say the hundreds of newly identified sites likely represent only a small fraction of the archaeological remains still hidden beneath the Amazon canopy. Additional LiDAR surveys and field investigations will be needed to confirm the estimated number of earthworks and better understand how these ancient communities were organized.
As exploration continues, archaeologists expect further discoveries could provide new insights into one of the world’s least understood ancient civilizations and fundamentally change perceptions of the Amazon’s human history.
