A semiarid east-west swath across Africa, environmentally transitional between the Sahara Desert (to the north) and equatorial rainforests (to the south), in which recent desertification and drought have been particularly severe.
The transitional zone of several hundred kilometres between semiarid deserts in northern Africa and the open woodland savanna to the south. It extends over 6000 kilometres from the Atlantic Ocean to the Red Sea.
The ecoclimatic region that borders the Sahara Desert to the south in the 6000 km (3720 mi) long, 500 km (310 mi) wide strip crossing the continent of Africa from the Atlantic Ocean to the Red Sea between the 100 mm (4") and 600 mm (24") isohyets of mean annual rainfall. It is characterized by low and erratic rainfall with little vegetation, most of which is seasonal. The word "Sahel" comes from the Arabic word for "edge".