Why are there two Sudans?

Sudan was traditionally the country with the largest land mass in Africa. This country was formed in 1956 based on the British colonial territory but like many colonial territories, it didn't hold people of the same ethnic, cultural and religious beliefs. The northern part of Sudan was traditionally Arabic speaking and Islamic believers. The southern parts were traditionally Nubian speakers and followers of the Coptic version of Christianity. Some parts of southern Sudan maintained traditional animist beliefs. The southern part was only incorporated with its northern neighbour in the nineteenth century. That incorporation had been resisted for most of that period because of religious and cultural intolerance.
The first Sudanese Civil War lasted from 1955 until 1972. The inevitable differences in the new republic were added to by economic problems. Wealth was seen to be focused in the north. This lasted until a coup put in place a new president, General Gaafar al-Nimeiry committed to grant the south a level of self-rule. However al-Nimeiry (under pressure from Islamists at home) went back on his commitments. He made Arabic the official language of the state, Sharia Law (traditional Islamic law) the law of the land and removed local autonomy from the South. This led to the Second Sudanese Civil War (1982 to 2005).
The Sudan Liberation Army under John Garang fought for political and economic control, cultural and religious freedom for Southern Sudan. Under international pressure this long destructive war came to an end in 2005 and an agreement was signed creating a government of national unity. It also allowed the people of South Sudan to vote whether they wanted independence. In 2011 they voted for independence and the state of South Sudan was created.