They rode in at dawn on horse and camel, stole livestock and burned houses, murdered the men and raped the women. The Arab militiamen known as Janjaweed have been responsible for much of the bloodshed in Sudan 's Darfur region, where some 70,000 have died and 1.6 million have been displaced over the past 22 months. On a continent so torn by war, the Janjaweed stand out for the speed and scope with which they carried out their bloody campaign against black African tribes, which the U.S. and others called genocide. "Our land is filled with corpses," says Mukhtar Yaya Juma, 37, a Sudanese refugee in Chad . "Only the blowing wind has buried them." The Janjaweed remain elusive. Even their name is something of a mystery, alternately translated as "devil on horseback" and a conflation of the Arabic words for horse and the G3 (Gewehr 3) assault rifle. In Darfur , the term simply means "outlaw." That's what many Janjaweed were before the Sudanese government released them from prison to help quell an insurgency by the region's non-Arab Muslims. Their specialty: targeting African tribes that supply recruits to the rebels. The Janjaweed gave Khartoum an enthusiastic, independent fighting force. And as international pressure mounted to stop the killing, they offered something more: an alibi. Says Dave Mozersky of the Brussels-based International Conflict Group: "If the government can convince enough people that Darfur is a tribal conflict and that they're innocent bystanders, then they'll have won."