The Sahel is often viewed as an area isolated from the surrounding region, and with its own special problems. But on ecological grounds, as well as for historical and contemporary political and economic reasons, the Sahel should instead be seen as the northern part of a larger regional whole which includes the more humid Sudanian zone. Desertification takes two distinct forms: desert spread, and induced desertification in more humid areas.

Saharan encroachment into Sahelian lands may occur gradually through growing aridity and resource abuse. Of more immediate concern here is human-induced, accelerated degradation of areas well south of the Saharan fringe. Deteriorated patches occur now with alarming regularity around centres of human activity, even well south into the Sudanian zone. In their struggle to survive, populations further overexploit resources in these focal points of desertification and gradually encourage their spread. The challenge is not "stopping the desert's advance from the north", but effectively managing renewable resources south of the desert.