The Sudan People's Liberation Army (SPLA), headed by Col. John Garang, was formed when several rebel groups banded together in 1982. The army is not seeking independence for the south as did rebel groups during the country's first civil war which lasted from 1956 to 1972. It is demanding greater regional autonomy, a larger voice in national affairs, and a bigger share of economic development.
In 1972, then-ruler Jaafar Nimeiry brought an end to the civil war, by giving the south semi-autonomy. The southern region is made up of Christians and animists, who resist what they see as unfair dominance by the country's Arab majority.
But relative calm was short-lived. In the early 80s, the south's resentment at being left out of most economic development, revocation of its semi-autonomous status, and implementation of Islamic law renewed unrest.
Nimeiry's rule ended in April 1985 and a military council ruled for one year. Last April elections brought Sadiq al-Mahdi to power. But polling was suspended in half of the southern districts because of rebel activity. The SPLA has added new nationwide elections to their list of demands.