Fascinating earthen formations hidden deep in Amazon reveal lost ancient societies of millions

The Amazon might not have been the untamed jungle we once thought.

The world’s largest tropical rainforest was allegedly once home to a sprawling civilization whose population numbered in the millions, according to a groundbreaking study in the journal Nature.

“Our findings overturn our understanding of the Amazon region’s past,” said the paper’s lead author, Martti Pärssinen at the University of Helsinki, Finland, New Scientist reported.

He and his team were focused on the Anquiry people, an Amazonian civilization that lasted from 600 BC to AD 850. However, until now, little was known about this ancient population as their territory comprised what was deemed “uninhabited pristine rainforest,” per Pärssinen.

Using canopy-penetration lasers, the researchers were able to survey over 1,700 square miles of dense Amazon rainforest, revealing vast earthworks — large formations comprising circles, squares, rectangles and octagons.

They discovered over 432 of these abandoned geoglyphs — which were created by excavating ditches and compiling the dirt into embankments — 400 of which were completely new to science.

Considering the vastness of Aquiry civilization, the scientists estimate there may be as many as 30,000 of these structures, which come in circles, squares and other geometric shapes.

The researchers estimated that the earthworks would’ve taken around 300 people to erect and maintain, suggesting that the population totaled between 1.25 and 3 million people at the civilizations zenith.

What purpose did these strange structures serve? Based on past excavations of Amazonian settlements, the researchers deduced that they were ceremonial “venues for gatherings, political decision-making and displays of chiefly generosity, ritual dancing, music, feasting, athletic competitions and ball games,” per Pärssinen.

Family dwellings were likely scattered around these community centers, the researchers surmised.

In addition, the earthworks were connected by an intricate series of straight roads, suggesting that they were part of a well-planned network rather than isolated jungle communities.

These findings ran counter to the romanticized visions of indigenous peoples living in harmony with nature. By contrast, the Aquiry had a significant impact on the jungle, clearing forests for both the earthworks and crops such as maize, squash and manioc.

They also notably cultivated Brazil nuts, peach palms and other produce.

While the cause of their demise in 850 AD is yet unclear, the discovery dispels “the notion of Amazonia as an untouched wilderness” until the arrival of European colonists, said Pärssinen.

“Ancient human societies played an important role in shaping the present-day tropical rainforest,” said the researcher.

Given the comparatively small sample size, the researchers estimate that there are thousands more ancient settlements lying in the rainforest waiting to be discovered and studied.