The region's many rebel groups agreed on Jan. 20, 2006 to join forces under the Alliance of Revolutionary Forces of Western Sudan, however, several months later, the rebels still were negotiating with the African Union and the Sudanese government through different leaders and factions.

There are two main rebel groups within the alliance. The larger one, the Sudanese Liberation Army/Movement, represents non-Muslim tribal Africans and is led by Minni Arcua Minnawi and Abdel Wahed Mohamed el-Nur.

The smaller one, the Justice and Equality Movement, represents non-Arab Muslims, headed by Dr. Khalil Ibrahim Muhammad.

The two divisions remain united in their opposition to Sudan, their motives developed for different reasons.

Sudanese Liberation Army/Movement
The SLA/M grew out of an armed self-defense militia formed by western Sudanese indigenous tribes.

Arable land in western Sudan has long been a source of conflict between Arab nomads, who want to use the land for grazing, and African tribes, who want to use it for farming.

During a famine in 1987, an Arab alliance formed in opposition to the farming communities of the African tribes, and in response, the tribes created militias for self-defense.

Three men now claim the presidency of SLA/M. Minni Arcua Minnawi, of the Zargawa tribe, has long been recognized as the troop commander of SLA/M, and as of 2005 was elected as its leader.

However, Abdel Wahed Mohamed el-Nur, the longtime political leader of SLA/M, has been the chief negotiator for SLA/M at peace talks in Abuja, Nigeria, and also claims SLA/M's presidency.

But on March 6, 2006, 19 of SLA/M's leaders denounced Nur in a public statement: "Abdel Wahed Mohamed el-Nur is determined to go it alone to consolidate his dictatorship and marginalize all the institutions of the movements in his drive to carry out his narrow-minded personal agenda."

This split further complicated negotiations in Abuja and a temporary leader of the SLM/A was appointed, Nur's deputy, Khamis Abddallah Abakr.

Justice and Equality Movement
In a 1989 coup, National Islamic Front leader Hassan al-Turabi helped overthrow President Sadeq al-Mahdi, clearing the way for Omar Hassan al-Bashir to take the leadership post.

Al-Turabi then incorporated non-Arab African Muslims into the political system of Sudan.

After al-Turabi reportedly tried to reduce his power, al-Bashir dissolved the government and purged it of the non-Arab African Muslims who went on to form JEM.

Long dominated by Islam, the government of Sudan is accused by JEM of being discriminatory and oppressive to non-Arabs. Statements from JEM's Web site accuse the government of offenses, including taking land from African tribes, systematic rapes, destruction of basic infrastructure such as water and electrical systems, and bombing of civilians.

The Web site also describes a complaint of both rebel groups -- attacks on camps of internally displaced persons. It is in defending these camps, made up mostly of non-Arab African Muslims and Africans, that the SLA/M and the JEM often encounter Janjaweed militia, who sometimes plunder the camps taking livestock, water and other resources, and sometimes women.

In January 2006, the two groups issued a joint statement:

"The two movements have agreed to join and coordinate all political, military and social forces, their international relations and to double their combat capacity in a collective body under the name, the Alliance of Revolutionary Forces of West Sudan."

While this presumably means that the two movements are operating under joint command, the agreement was signed by Ibrahim Khalil Mohammad and Minni Arcua Minnawi, which means that the faction of SLA/M still loyal to Abdul Wahed Mohammed el-Nur may not be party to it, even though they have been taking part in peace negotiations.

-- Compiled by A.C. Valdez for the Online NewsHour