While previous studies have demonstrated that people travelled across the Saharan mountains towards more fertile regions adjacent to the Mediterranean, the question of when, where and how they did so has remained uncertain. Such a migration would almost certainly have required the presence of ‘green corridors’ that provided water and food, but the existence of such corridors also remained uncertain.
In a new study published in PLOS ONE, a team of researchers used paleoclimatic modelling to reconstruct the climate during the last interglacial period to investigate how the monsoon rains would have flowed off the trans-Saharan mountains and across the landscape. The model suggested that even after accounting for evaporation and absorption by the sand, there would still have been enough water for three river systems, now buried, to make it across the desert about 100,000 years ago.
The researchers suggest that the westernmost of the three systems, the Irharhar river, would have been 100 kilometres wide and largely perennial, making it the best candidate for the route of human migration across the region.
This story was published in the November 2013 edition of Geographical Magazine