Emotionally, they are walking dead men who count their future in hours. This makes them often ruthless, as if they think everyone might as well go to the next life with them. Many of them have seen their families murdered and their villages burned. You can imagine how you would feel if your hometown were wiped away and all your family killed by an enemy whom you now roam the land to find and kill so you can died in peace.
Among the rebels are the Sudan Liberation Movement, the Sudan Liberation Army, the Justice and Equality Movement, and several others. There are other groups in Chad, and they travel across the borders as they please. Where they get their guns and money is often a mystery, but Darfur has been filled with automatic weapons from the time when Libya attacked Chad and used Darfur as a staging area. Also, it must be understood that Sudan is aligned with radical Islamic groups and is, as a separate matter, letting China get most of its oil. So some Western interests and some surrounding countries are thought to be involved in supporting the rebel groups. It is sad how ordinary people suffer when these chess games are played.
Nearly half of Africa is covered by the pastoral lands of herding villages, and much of this land has great wealth below and poor people above. They are among the three hundred million Africans who earn less than a dollar a day, and who are often pushed out of the way or killed for such things as oil, water, metal ore, and diamonds. This makes the rise of rebel groups very easy.