The war between the northern and southern Sudanese is one of the longest and most complex in Africa, driven by religious schisms, racial politics, oil, and an especially convoluted colonial legacy. The first period of fighting began in 1955 and lasted until 1972. During the second period of conflict, between 1983 and 2005, more than two million people were killed and hundreds of thousands of starving people became refugees, including the Lost Boys, southern Sudanese children who were cast off to wander for hundreds of miles across the savannah, dodging lions and bombers. One of the terms of the peace agreement that ended the fighting in 2005 was a referendum held in 2011 in which southern Sudanese voted overwhelmingly for independence from the north. Within this broader conflict, the rebellion in the Nuba Mountains may be the most intractable. It is also the one causing the most intense violence and suffering right now. The Nuba rebel army, based within Sudan but with support from South Sudan, has been willing to fight far better equipped Sudanese government forces.