The Arab-dominated government in Khartoum has armed nomadic Arab herdsmen, or Janjaweed, against rival African tribes.
The crisis began in 2003 with a rebellion that sought to end the marginalization of non-Arab tribes by the Arab-dominated government.
Cleavages have opened between the Arab-dominated government and the Arab militias.
But this harsh reaction failed to pacify the south, as some of the mutineers escaped to remote areas and organized resistance to the Arab-dominated government of Sudan.
The Arab-dominated government envisioned agricultural development in the South and northern farmers continually encroached upon the fertile southern plains.
For 20 years rebels in southern Sudan have sought to topple the Arab-dominated government in the north.
For 15 years southern rebel groups have been fighting successive Arab-dominated governments for more autonomy, racial equality and religious freedom.
The conflict in Sudan is waged by an Arab-dominated government against non-Arab people in Darfur.
The refugees, who are black Africans, have reported attacks by largely Arab militias affiliated with the Arab-dominated government in Khartoum.
The conflict began when a non-Arab rebel group seeking more wealth and autonomy for Darfur from the Arab-dominated government attacked an army post in 2003.
