The Sudan, from the Arabic bilâd as-sûdân or "land of the Blacks" (an expression denoting West and Central Africa), is a geographic region stretching from West to Eastern Africa. The phrase "The Sudan" is also used by some to refer specifically to the modern-day country of Sudan, the savanna of which forms much of the larger region.
The Sudan extends in a band across Africa from Mali (formerly known as French Sudan when it was a French colony) in the west to the western edge of the Ethiopian Highlands in the east. To the north lies the Sahel, a more arid Acacia savanna region which in turn borders the Sahara desert, and to the east Ethiopia (called al-Ḥabašah in Arabic). The grass in the Sudan is longer than in the Sahel, and because the region receives more rainfall than the Sahel it is more suitable for farming.
The region is divided by the Cameroon Highlands into eastern and western halves. To the south of the western part is the Guinea forest-savanna mosaic. To the east in Sudan are the Sudd flooded grasslands, and to the south the Northern Congolian forest-savanna mosaic.