For 21 years, the Sudan People’s Liberation Army (SPLA) and its allies fought against the Sudanese government for political autonomy from Khartoum. The conflict, often described as one between the Arab Muslim north and the Christian tribal south, killed an estimated 1.9 million people and displaced more than four million southern Sudanese people. In 2005, both sides signed the Comprehensive Peace Agreement (CPA), which ended the conflict. In 2011, the people of southern Sudan gained independence. However, tensions between Sudan and South Sudan continued following the secession. After an armed conflict over disputed oil-rich regions in Unity and South Kordofan, in mid-2012, the two nations made progress towards an agreement on the demarcation of the border and the destination of oil revenues. Nevertheless, both countries continue to support rebel groups operating in the other’s territory, and conflict persists in Sudan’s South Kordofan and Blue Nile states. Divisions within the ruling Sudan People’s Liberation Movement (SPLM) in December 2013 plunged the country into another crisis, which quickly took on ethnic undertones. Fighting broke out between supporters of President Salva Kiir, a member of the Dinka tribe, and ousted vice president Riek Machar, a Nuer. Thousands have been killed, and the UN Office for the Coordination of Humanitarian Affairs (OCHA) reported in August 2015 that 1.6 million people have been internally displaced by the conflict. Attempts at peace talks have so far failed to achieve stability in South Sudan.