Traces of a vast ancient civilisation have been found beneath the Amazon rainforest

The study focused on the ancient Aquiri culture, which flourished in what is now the Brazilian state of Acre from around the 6th century BC to the 9th century AD.

Using LiDAR technology — aerial laser scanning that allows the surface of the earth to be ‘seen’ through dense vegetation — the researchers surveyed around 4,500 square kilometres of jungle.

Beneath the trees, they discovered more than 400 well-preserved archaeological sites, including huge earthworks, ceremonial sites and straight roads.

Details

Having studied the sites found, the researchers calculated how many such structures might have existed across the entire territory of the Aquiri culture, covering an area of around 183,000 square kilometres.

They estimate that there were more than 20,000 large ceremonial centres there.

Based on this data, the scientists concluded that as early as the beginning of the Common Era, between 1.25 and 3 million people may have lived there. If these calculations prove correct, the population of the entire Amazon region at that time could have numbered in the tens of millions.

The study also revealed that the inhabitants actively altered their environment.

They cleared bamboo forests, cultivated maize, cassava and pumpkins, built wide roads between settlements and deliberately cultivated useful tree species, including the Brazil nut and the peach palm.

According to the authors, human impact on the Amazonian ecosystem in the past was significantly greater than previously thought.

No typical palaces or temples have survived to the present day, as there is virtually no natural stone in this region.

Instead, archaeologists are finding huge earthen geometric structures — so-called geoglyphs. It is these that bear witness to the scale of this ancient civilisation.

Scientists note that Aquiri was not a single state, but a network of numerous communities linked by roads, trade and shared ceremonial centres.

What remains a mystery

Researchers still do not know which languages the inhabitants of Aquiri spoke or what they called themselves.

It is also unknown why this civilisation disappeared rather rapidly around 850 AD. Around the same period, the Classic Maya civilisation in Central America also declined.

Limitations of the study

The authors emphasise that the population figure has been calculated using a statistical model based on LiDAR data and archaeological research. This is a scientific estimate, not a direct count of the inhabitants.

Nevertheless, the discovery of hundreds of new archaeological sites significantly alters our understanding of the Amazon’s past and indicates the existence of far more complex societies here than previously thought.

Source

Study:

Over 20,000 pre-colonial earthworks in the south-western Amazon.

Journal: Nature (2026).