Sudan, a vast indefinite region of some 2,000,000 square miles (5,200,000 km2) in northern Africa. It extends from the Red Sea westward to the Atlantic Ocean and from the Sahara southward to the tropical rain forests of central and western Africa. Most of the region lies within Eritrea, Ethiopia, Sudan, Chad, Niger, Mali, Burkina Faso, Senegal, Gambia, and Mauritania. The Sudan is primarily a grassland region, with short grasses in the north and tall grasses and scattered trees in the south. The part just south of the Sahara, called the Sahel, is an area where droughts are frequent, bringing widespread hunger and starvation.

Annual rainfall varies from about 10 inches (250 mm) in the north to roughly 50 inches (1,250 mm) in the south, most of it falling during the summer months. Temperatures are generally high throughout the year.

The Sudan is rich in wildlife. However, human settlements, the grazing of domestic herds, and hunting for sport have almost exterminated the large mammals—such as elephants, lions, and giraffes—in many parts of the Sudan. These animals are rarely seen outside the game reserves and national parks that have been established by some countries of the Sudan.

The name Sudan is derived from an Arabic term meaning “land of the blacks,” but traffic between this region and northern areas led to racial mixture many centuries ago. In the east, there are people of Arab as well as black ancestry. In the west, the people are predominantly black, with some Berber peoples (who are Caucasians), and some people of mixed Berber and black heritage.