The war in Darfur (western Sudan) has been going on for two years, and mainly consists of pro-government forces (who are Sudanese of Arab ancestry) attacking non-Arab tribes. The government denies aiding the raiders, and says the only fighting in the region involves dealing with local rebels. The rebels were a minor problem, until the government armed and organized militias from nomadic Arab tribes, who were already skirmishing with non-Arab tribes of farmers. Now the rebels, who were mostly non-Arabs, really had something to rebel against.
Numbers are approximate
Armed Forces of Sudan 32,000
Jinjaweed Militia 15,000
People's Defense Forces 7,000
The Jinjaweed are the government armed nomads who are committing most of the atrocities. The armed forces, police and paramilitary People's Defense Forces often join in.
Sudan Liberation Army 4,000
Justice & Equality Movement 2,000
Movement for Reform & Democracy 1,000
Many of these rebels are simply organized tribal defense forces, trying to provide some resistance to the raiders.
African Union Peace Monitors 6,900