A vegetation zone between desert and savannah conditions where rainfall is irregular and unpredictable, and the vegetation is scrubland. The name is most commonly applied to the area south of the Sahara including parts of Mauritania, Chad, Mali, Senegal, Burkina Faso and Niger.

The area frequently suffers from drought and famine.

The nature of rivers in the Sahel zone is exceptional: because of the imbalance between rainfall and evaporation, no permanent surface water exists for long periods of time.