Huge Network Of Ancient Cities Uncovered In The Amazon Rainforest

Published January 16, 2024
Updated January 19, 2024

"They completely modified the valley at a level we've never seen. It's incredible."

Upano Valley Ancient Cities

Rostain et al.Lidar scans of the Upano Valley in Ecuador.

Deep within the Amazon, researchers recently discovered a network of 2,500-year-old cities unlike anything ever before seen in the region — and it’s changing historians’ understanding of ancient life in the rainforest.

Laser scans revealed the existence of thousands of mounds that mark the locations of long-gone houses, plazas, and monuments that were connected by “sophisticated” roads and surrounded by terraced farmland. This new discovery is the largest and earliest example of a large-scale agricultural civilization in the South American rainforest.

“This is older than any other site we know in the Amazon. We have a Eurocentric view of civilisation, but this shows we have to change our idea about what is culture and civilisation,” Stéphen Rostain, director of research at the National Centre for Scientific Research in France, who led the study, told BBC.

Rostain and his colleagues’ findings were just published in the journal Science.

The settlements were likely inhabited between 500 B.C.E. and 600 C.E. While researchers were not able to pinpoint exactly how many people lived in the urban centers, they estimated that the area’s population may have reached over 100,000 at one point.

“It changes the way we see Amazonian cultures,” said study co-author Antoine Dorison. “Most people picture small groups, probably naked, living in huts and clearing land — this shows ancient people lived in complicated urban societies.”

Ecuador’s Upano Valley has been of interest to archaeologists and historians for decades, but it wasn’t fully mapped out until 2015. That year, Ecuador’s National Institute for Cultural Heritage funded a Light Detection and Ranging (LiDAR) scan of the area, revealing for the first time the true scale of the civilization that once existed in the region.

Beneath the massive canopy of trees that make up the Amazon rainforest, laser scans revealed a network of roughly 6,000 mounds clustered at 15 separate sites. What’s more, each urban center was connected by an intricate system of roads.

Lidar scans further showed these 6,000 mounds were arranged in groups of three to six units surrounding a central square plaza. Researchers believe that the mounds mark the location of homes, but some of the sites may have been used for ceremonial purposes.

Most notably, however, Rostain clarified to Science News that these were not a series of small villages linked by roads, but rather “an entirely human-engineered landscape” built by skilled urban planners. One of these interconnected roads stretched out for roughly 16 miles.

Lidar Scans Overview

Rostain et al.A map showing the density of the Upano Valley based on lidar scans.

“The road network is very sophisticated. It extends over a vast distance, everything is connected. And there are right angles, which is very impressive,” Dorison told the BBC.

Several sites indicate that the region was inhabited for roughly 2,000 years by at least five different cultural groups beginning around 500 B.C.E.

Archaeologist Christopher Fisher of Colorado State University, who was not involved with the study, called the discovery “a gold rush scenario, especially for the Americas and the Amazon.”

“Scientists are demonstrating conclusively that there were a lot more people in these areas, and that they significantly modified the landscape,” he said. “This is a paradigm shift in our thinking about how extensively people occupied these areas.”

The first evidence that a city once stood in the Upano Valley was initially uncovered in the 1970s, but without modern laser technology, the full extent of the settlement was never realized. Now, the latest evidence shows that this ancient society may have been even more complex than many Maya settlements.

Perhaps even more surprising is that Rostain said he had been warned against conducting research in the Amazon early on in his career. According to the professor, it was widely believed that no ancient groups could have thrived in the inhospitable conditions of the Amazon.

Upano Valley Mounds

Rostain et al.Mounds spread across the Upano Valley.

“But I’m very stubborn, so I did it anyway. Now I must admit I am quite happy to have made such a big discovery,” Rostain said.

While there is still little known about the people who once called the Amazon home, future research can hopefully reveal more about who they were and what their society was like. After all, this is “just the tip of the iceberg,” according to study co-author Fernando Mejía.

“Such a discovery is another vivid example of the underestimation of Amazonia’s twofold heritage: environmental but also cultural, and therefore Indigenous,” the research team wrote in the study. “We believe that it is crucial to thoroughly revise our preconceptions of the Amazonian world and, in doing so, to reinterpret contexts and concepts in the necessary light of an inclusive and participatory science.”

After learning about this ancient city uncovered in the Amazon, read about two other lost cities uncovered in Bolivia’s rainforest. Or, learn about the 14th-century villages found in the Amazon that were arranged like constellations.

Austin Harvey
A staff writer for All That's Interesting, Austin Harvey has also had work published with Discover Magazine, Giddy, and Lucid covering topics on mental health, sexual health, history, and sociology. He holds a Bachelor's degree from Point Park University.
John Kuroski
John Kuroski is the editorial director of All That's Interesting. He graduated from New York University with a degree in history, earning a place in the Phi Alpha Theta honor society for history students. An editor at All That's Interesting since 2015, his areas of interest include modern history and true crime.
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Harvey, Austin. "Huge Network Of Ancient Cities Uncovered In The Amazon Rainforest.", January 16, 2024, Accessed June 13, 2024.