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.
List of heads of state of South Sudan
The region of Southern Sudan (currently the independent republic of South Sudan) became autonomous for the first time, within Sudan, in 1972, through the Addis Ababa Agreement, and its local government had five presidents until 1983, when the Sudanese central government revoked the autonomy. Autonomy was gained again in 2005, through the Comprehensive Peace Agreement meant to end the Second Sudanese Civil War, and the position of president of Southern Sudan was restored. Then, on 9 July 2011, South Sudan became independent and a new constitution was adopted.