Tom Coulthard from the University of Hull, along with colleagues from other institutions, simulated paleoclimates in the region that suggested three major river systems likely existed in North Africa 130,000 to 100,000 years ago, although they are now largely buried under desert dunes.
When flowing they would have created fertile habitats for animals and vegetation and served as "green corridors," providing likely routes of human migrations across the region, the researchers said.
While previous studies have shown people traveled across the Saharan mountains toward more fertile Mediterranean regions, when, where and how they did so has long been a subject of debate.
"It's exciting to think that 100,000 years ago there were three huge rivers forcing their way across 1,000 kilometers (620 miles) of the Sahara desert to the Mediterranean -- and that our ancestors could have walked alongside them," Coulthard said.
In addition to rivers, the researchers said, their simulations predicted massive lagoons and wetlands in northeast Libya, some of which may have been as large as 27,000 square miles.
The study has been published in the journal PLoS ONE.