The part just located at the south of the desert is a steppe, a semi-arid region, called the Sahel. It is the ecoclimatic and biogeographic zone of transition in Africa between the Sahara desert to the north and the Sudanian Savanna to the south. The Sudanian Savanna is a broad belt of tropical savanna that runs east and west across the African continent, from the Atlantic Ocean in the west to the Ethiopian Highlands in the east.