The Second Sudanese Civil War was a conflict from 1983 to 2005 between the central Sudanese government and the Sudan People's Liberation Army. It was largely a continuation of the First Sudanese Civil War of 1955 to 1972. Although it originated in southern Sudan, the civil war spread to the Nuba mountains and the Blue Nile. It lasted for 22 years and is one of the longest civil wars on record. The war resulted in the independence of South Sudan six years after the war ended.

Roughly two million people died as a result of war, famine and disease caused by the conflict. Four million people in southern Sudan were displaced at least once (and normally repeatedly) during the war. The civilian death toll is one of the highest of any war since World War II and was marked by numerous human rights violations, including slavery and mass killings.

The Sudan People's Liberation Movement (SPLM) (Arabic: الحركة الشعبية لتحرير السودان, Al-Ḥarakat ash-Shaʿbiyyat liTaḥrīr as-Sūdān) is a political party in South Sudan. It was initially founded as the political wing of the Sudan People's Liberation Army (SPLA; a key belligerent of the Second Sudanese Civil War) in 1983. On January 9, 2005 the SPLA, SPLM and Government of Sudan signed the Comprehensive Peace Agreement, ending the civil war. SPLM then obtained representation in the Government of Sudan, and was the main constituent of the Government of the then semi-autonomous Southern Sudan. When South Sudan became a sovereign state on 9 July 2011, SPLM became the ruling party of the new republic. SPLM branches in Sudan separated themselves from SPLM, forming the Sudan People's Liberation Movement-North. Further factionalism appeared as a result of the 2013-2014 South Sudanese Civil War, with President Salva Kiir leading the SPLM-Juba and former Vice President Riek Machar leading the Sudan People's Liberation Movement-in-Opposition.

Although the party has not adhered to one consistent ideology since the independence of South Sudan and by extension the effective end of the New Sudan concept, and many factions exist, it has been described as "being on the left of centre ideological[ly] speaking," and section IV.2 of the party manifesto states support for a regulated market economy with similar elements to social democracy.