What boundary did the Sahara desert form of the roman empire?

The Sahara Desert served as the southern boundary of the Roman Empire, acting as a natural barrier that limited expansion and access to territories beyond its vast arid expanse. This desert region helped define the limits of Roman control in North Africa, where the empire maintained its influence primarily along the Mediterranean coast and in regions like Egypt and Numidia. The harsh conditions of the Sahara made it difficult for Roman forces to effectively govern or conquer the interior lands beyond the desert.