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. The Sahel, a belt of drier grasslands and acacia savannas, lies to the north, between the Sudanian savanna and the Sahara Desert. To the south the forest-savanna mosaic forms a transition zone between the Sudanian savanna and the Guineo-Congolian forests that lie nearer the equator.