Researchers have found the remains of several “lost cities” in the Amazon rainforest which seem to date since pre-Columbian discovery.

The Upper Xingu, in west Brazil, was believed to be a virgin forest. However, the vestiges of a pristine network of settlements point out to a civilization that flourished there long time ago.

28 towns, villages and hamlets, as well as a road network linking them, have been unearthed this way by anthropologists lead by Michael Heckenberger of the University of Florida. “These are not cities, but this is urbanism, built around towns…. If we look at your average medieval town or your average Greek polis, most are about the scale of those we find in this part of the Amazon,” said the lead researcher.

The settlements uncovered at the headwaters of the Xingu River are now believed to have been populated since the 15th century. 50,000 people are supposed to have occupied the 20,000 square kilometers of forest.

The remnants also indicate extensive human activities, what’s left from cooking utensils made of wood suggesting this. Bridges on several roads, as well as canoe canals along them are incontestable proofs of the existence of the pristine civilization. During that period of time, the occupants of the “garden cities” (as Heckenberger named them in Science) carved roads through the Amazon jungle, according to satellite pictures.

“Some of the practices that these folks hammered may provide alternative forms of understanding how to do low level sustainable development today,” Heckenberger said.

Heckenberger and his colleagues first announced the discovery of the settlements in a 2003 Science paper. The largest date from around 1250 to 1650, when European colonists and the diseases they brought likely killed most of their inhabitants.