Sudan has oil, and negotiations to share South Sudan’s oil wealth have been part of the issue between the Muslim north and the mainly Christian and animist south. It has spawned what the UN calls "the world's worst humanitarian crisis".
The historic conflict between Arabs and Africans is a recurring theme in Sudan, but it would be wrong to assume that it is always Arabs who are the victors, and Africans the vanquished.
In camps for internally displaced people (IDP) in Darfur, where the United Nations' World Food Program (WFP) works, there are many examples of families and communities whose stories do not fit into simple stereotypes.
While the majority of the displaced are black Africans who have fled attacks by the Arab Janjaweed militia, there are also displaced Arab communities, whose villages were attacked by African groups, and who are victims of inter-African ethnic fighting. There are even parts of South Darfur where the WFP currently cannot work because of a dangerous traditional conflict between rival Arab groups.
The latest conflict began in early 2003, when two Darfur rebel groups took up arms against the Arab-led Islamic government in Khartoum, citing discrimination against the region's black tribes. The Sudanese government armed and organized a local Arab militia, known as the Janjaweed, to target local communities that were suspected of sympathizing with the rebels.
U.N. officials say as many as 200,000 people may have been killed by violence and disease as a result of the attacks.