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.
Constitution of South Sudan
A version of the constitution was ratified on 7 July 2011 by the South Sudan Legislative Assembly. It came into force on the day of independence of South Sudan (9 July 2011) after being signed by the president of the republic. The Constitution replaced the existing 2005 Interim Constitution of Southern Sudan. The constitution establishes a presidential system of government headed by a President who is Head of State, Head of Government, and the Commander-in-Chief of the armed forces.