South Sudan–Sudan border

North and south

Under British rule the north accepted colonial government relatively quickly while the south resisted, and Britain modernised the north while mostly keeping order in the south. The gap in development lasted for decades.^[1] After Sudan became independent in 1956, many southerners took up arms against northern governments that sought to extend Islamic law and culture across the country.^[1]

The civil war ended with the Comprehensive Peace Agreement, signed on 9 January 2005. It gave the south its own government and promised a referendum on independence within six years. Three sensitive border areas got special status: Abyei was to vote on which side to join, and Southern Kordofan and Blue Nile, northern states where many had fought for the south, were to hold “popular consultations”.^[2]

A new border

Southerners voted overwhelmingly for independence in a referendum held on 9–15 January 2011, and South Sudan became independent on 9 July 2011.^[1] The line between them, until then internal, became an international border.

Some issues were settled quickly, including a September 2011 agreement to open several border crossings. Others were not. South Sudan’s oil could only be exported through Sudan’s pipelines and ports, and when the two could not agree on fees, Sudan began confiscating South Sudanese oil in December 2011, and in January 2012 South Sudan shut down its oil fields.^[3]

Heglig and Abyei

The unresolved demarcation of the border led to repeated clashes. In March 2012 fighting broke out over Heglig, an area generally recognised as part of Sudan pending final demarcation and home to one of its most important oil fields, but also claimed by South Sudan. South Sudanese troops occupied it for several days in April, then withdrew under pressure from the AU and the UN, which held the occupation illegal. Fighting spread to Abyei before subsiding in May.^[3]

Abyei, which straddles the line and is claimed by both, had already seen deadly clashes in 2011 that drove more than 100,000 people from their homes. On 27 June 2011 the UN Security Council created a peacekeeping force for it, UNISFA.^[4] The referendum promised in 2005 was never held; in October 2013 Dinka residents aligned with South Sudan held their own vote, which was not internationally recognised.^[3]

A set of agreements on oil fees, borders and other issues was signed in September 2012, and South Sudan resumed oil production in April 2013 after both sides committed to implement them.^[3]