A 'lost valley of cities' built thousands of years ago has been found in the Amazon

• A group of lost cities dating back thousands of years was discovered in the Amazon rainforest.
• Scientists said the site, which was found in Ecuador, was occupied by the Upano people.

A group of cities that had been hidden for thousands of years by the Amazon jungle has been discovered in Ecuador, The Associated Press reported.

A team of archaeologists working in the Upano area of eastern Ecuador found an intricate network of roads and canals connecting houses and plazas, challenging previous beliefs that the Amazon was only home to nomadic peoples or small settlements.

"The settlements are much bigger than others in the Amazon," Stéphen Rostain, the director of investigation at the National Centre for Scientific Research in France and lead researcher, said, per the New Scientist.

"They are comparable with Maya sites," he added.

The cities, which were constructed from around 2,500 years ago and inhabited for around 1,000 years, had an estimated population of at least 10,000, a coauthor of the study, Antoine Dorison, said.

To survey the city, researchers flew over the region and used Light Detection and Ranging (Lidar) laser sensors to pick out its remains below the dense vegetation.

The Lidar technology identified 6,000 rectangular platforms that were arranged around plazas. They likely served as residences and ceremonial spaces, scientists said.

"It was a lost valley of cities," Rostain said, per The AP. "It's incredible."

Dorison said the most notable part of the findings was the network of roads leading to and from many of the platforms.

"The road network is very sophisticated. It extends over a vast distance, everything is connected. And there are right angles, which is very impressive," he said, per the BBC.

In the platforms, researchers discovered pits, hearths, and artifacts like jars and stones used for plant grinding, shedding light on the daily lives of the inhabitants.

University of Florida archaeologist Michael Heckenberger, who was not involved in the study, told The AP that "for the region," the society was "really in a class of its own in terms of how early it is."