"The settlements are much bigger than others in the Amazon,” says Stéphen Rostain at the French National Center for Scientific Research in Paris. “They are comparable with Maya sites.”

What’s more, at between 3000 and 1500 years old, these cities are also older than other pre-Columbian ones discovered in the Amazon. Why the people who built them disappeared isn’t clear.

  • I’m not sure if you’re referring to the Conquistadors, but this site was abandoned quite a long time before that.

    All the Upano artefacts dated by Rostain’s team are older than 1500 years, however, suggesting the settlements in the valley were abandoned after this time, long before the colonial era. Why isn’t clear, but the team has found layers of volcanic ash, so it is possible a series of eruptions forced people to leave the valley.