In 2018, researchers used satellite imagery to identify 81 ancient earthwork sites in the Amazon, providing evidence of pre-Columbian settlements

The "untouched" Amazon rainforest often pictured in nature documentaries as an empty, unbroken expanse of forest, was in fact home to planned settlements centuries before European contact. Archaeologist Jonas Gregorio de Souza and colleagues reported this in a 2018 Nature Communications article, "Pre-Columbian earth-builders settled along the entire southern rim of the Amazon." Using satellite imagery, the team identified 81 previously unmapped archaeological sites in the Amazon, revealing fortified villages and ceremonial earthworks built around the early-to-mid 1400s, in the closing decades of Europe's medieval period. This finding adds to a body of evidence, built up over a series of studies in recent years, that the Amazon was not the empty wilderness of popular imagination but a landscape that supported dense, complex societies.

What the satellites actually picked up on under the canopy

The team of archaeologists in the Nature Communications article studied the Upper Tapajós Basin, a place previously thought to have few archaeological sites due to the region's lack of prior exploration, and found 81 different sites containing 104 individual earthworks (several sites contained more than one structure) made by people who constructed geometric enclosures, circular and square ones among them, meant to serve as ceremonial or defensive structures. According to a 2018 summary of the study by Smithsonian Magazine, 24 of the chosen excavation sites had stone tools, pottery, sunken roads, house platforms, and darkened, nutrient-rich soil known as terra preta, which was used as fertilizer and is evidence that there had been a large human settlement in the area.

The article says charcoal from these sites was carbon-dated to between 1410 and 1460, just before European colonization disrupted many of these societies. The sites also apparently formed a chain 1,800 kilometers long that hugged the edge of the southern Amazon, and could suggest that this area, contrary to popular belief, was not uninhabited wilderness but rather a settled land with Arawak-speaking people living in complex societies with their own social order.

The plot twist

A to a 2026 study titled “Over 20,000 precolonial earthworks in the Southwest Amazonia,” published in the journal Nature, by Martti Pärssinen et al, used LiDAR imaging technology, which can see through the forest canopy, to survey roughly 4,500 square kilometers across the Brazilian states of Acre and Amazonas, part of the wider southwest Amazonia region the study covers. That survey documented 432 earthworks, 396 of which had not been previously recorded (36 were already known).

Extrapolating from the density of earthworks found in the surveyed area, the researchers estimate that southwest Amazonia as a whole may contain more than 20,000, and potentially up to 30,000, such structures. These are attributed to a distinct society the researchers call the Aquiry civilization, which peaked between roughly 100 and 300 CE and is estimated to have had a population of between 1.25 million and 3 million people.

Why should this matter

If you've ever watched a nature documentary growing up that romanticized the idea of there being "untouched" civilizations in the Amazon, this may come as quite the surprise to you. The Amazon was not the empty wilderness that needed to be conquered and transformed into settlements and cities fit for Western standards by the government-sanctioned, corporate-funded explorers and soldiers of the time. It was, and remains, home to people who lived in complex societies and built settlements, roads, and large-scale earthworks with deliberate planning. These findings continue to revise the historical record that once portrayed the region as unoccupied land.