A few thousand years ago, the Sahara Desert wasn’t such a dry place. Researchers have discovered a river network that may have flowed as recently as 5000 years ago in the western end of the desert under what is now Mauritania. 

Researchers found evidence of the waterway in radar images taken by a Japanese Earth observation satellite. Previous geological analysis of the ocean floor off the coast of West Africa dating back 120,000 years ago seemed to reveal river-borne sediment, but there are no rivers that currently flow into the Atlantic from the western Sahara. The radar images showed that the river beds underneath the desert connect to the Cap Timiris Canyon, a deep underwater canyon off the coast of Mauritania. 

The French-led research team, writing in the journal Nature Communications, proposes that a humid period in Africa between 11,700 and 5000 years ago activated this paleo river, which may have connected to the Tamanrasett River, a proposed river system that scientists hypothesize flowed across the northwestern part of the continent. 

[h/t The Guardian]

All images from Skonieczny et al., Nature Communications (2015)