History of Sudan
The modern Republic of Sudan was formed in 1956 and inherited its boundaries from Anglo-Egyptian Sudan, established in 1899. For times predating 1899, usage of the term "Sudan" for the territory of the Republic of Sudan was somewhat anachronistic, and may have referred to the more diffuse concept of the Sudan.
States of Sudan
Anglo-Egyptian Sudan had eight "mudiriyat", or provinces, which were ambiguous when created but became well defined by the beginning of World War II. The eight provinces were: Blue Nile, Darfur, Equatoria, Kassala, Khartoum, Kurdufan, Northern, and Upper Nile. In 1948, Bahr al Ghazal split from Equatoria.