The inhabitants of Sudan are divided into two main groups. Those who live mainly near the Nile consist of Arab and Nubian groups; they are Muslim (mostly of the Sunni branch), speak Arabic (the country's official language), and follow Arab cultural patterns (although only relatively few are descended from the Arabs who emigrated into the region during the 13th–19th cent.). The westerners, so called because they immigrated (primarily in the 20th cent.) from W Africa, are also Muslim, live mostly in the southern part of Sudan, and work as farmers or agricultural laborers. Other ethnic groups include the Beja in the northeast and the Fur in the southwest.
The great majority of the country's population live in villages or small towns; the only sizable cities are Port Sudan, Wad Madani, Al Ubayyid, and the conurbation of Khartoum, Omdurman, and Khartoum North. The desert and semidesert of the center and north are largely uninhabited.