The northern states cover most of the Sudan and include most of the urban centers. Most of the 22 million Sudanese who live in this region are Arabic-speaking Muslims, though the majority also uses a non-Arabic mother tongue--e.g., Nubian, Beja, Fur, Nuban, Ingessana, etc. Among these are several distinct tribal groups: the Kababish of northern Kordofan, a camel-raising people; the Jaíalin and Shaigiyya groups of settled tribes along the rivers; the semi-nomadic Baggara of Kordofan and Darfur; the Hamitic Beja in the Red Sea area and Nubians of the northern Nile areas, some of whom have been resettled on the Atbara River; and the Negroid Nuba of southern Kordofan and Fur in the western reaches of the country.

The southern region has a population of around 6 million and a predominantly rural, subsistence economy. Except for a ten-year hiatus, southern Sudan has been embroiled in conflict, resulting in major destruction and displacement since independence. More than 2 million people have died, and more than 4 million are internally displaced or have become refugees as a result of the civil war and war-related impacts. The southern Sudanese practice mainly indigenous traditional beliefs, although Christian missionaries have converted some. The south also contains many tribal groups and many more languages than are used in the north. The Dinka--whose population is estimated at more than 1 million--is the largest of the many black African tribes of the Sudan. Along with the Shilluk and the Nuer, they are among the Nilotic tribes. The Azande, Bor, and Jo Luo are "Sudanic" tribes in the west, and the Acholi and Lotuhu live in the extreme south, extending into Uganda.

In 2005, Sudanís population reached an estimated 40.2 million. A new census is planned for 2007. The population of metropolitan Khartoum (including Khartoum, Omdurman, and North Khartoum) is growing rapidly and ranges from 6-7 million, including around 2 million internally displaced persons from the former southern war zone as well as western and eastern regions affected by drought, conflict, and marginalization. In Darfur, there are an estimated 1.8 million internally displaced persons and another 220,000 refugees in neighboring Chad--200,000 in 12 camps and 20,000 in the border area.