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 countries where Arabic is an official language
Arabic (alongside English) was an official language in South Sudan from 1863 (these days a part of Egypt Eyalet (1517–1867)) until 2011 (that time the independent state Republic of South Sudan), when the former government canceled Arabic as an official language. Since 2011 English is the sole official language of South Sudan. The Arabic dialect Juba Arabic is still the lingua franca of the people in South Sudan.