structural:expansion, linguistic:translation, structural:scholar_edition
Geography

The Sahel spans 5,900 km (3,670 mi) from the Atlantic Ocean in the west to the Red Sea in the east, in a belt several hundred to a thousand kilometers (c. 600 miles) wide. It covers an area of 3,053,200 square kilometers (1,178,850 sq mi).

Representing a climatic and ecological transition zone with hot semi-desert and steppe conditions, the Sahel region borders the more humid Sudanian savannas to its south and the dry Sahara desert to the north. This ecoregion is also called the Sahelian Acacia savanna in honour of its most prominent and very drought tolerant genus of tree.

The topography of the Sahel is mainly flat; most of the region lies between 200 and 400 meters (660 and 1,310 ft) in elevation. Several isolated plateaus and mountain ranges rise from the Sahel (e.g. Marrah Mountains, Aïr Mountains, Ennedi Plateau), but are designated as separate ecoregions because their flora and fauna are distinct from the surrounding lowlands (e.g. East Saharan woodlands). Annual rainfall varies from around 100–200 mm (4–8 in) in the north of the Sahel to around 700–1,000 mm (28–39 in) in the south.