Abyei is the disputed region on the border between Sudan and South Sudan. Its status remained unresolved when South Sudan became independent in 2011, making it one of the most sensitive issues between the two countries.
The Abyei Area was defined through the 2004 Abyei Protocol, incorporated into the Comprehensive Peace Agreement that ended Sudan’s Second Civil War. The protocol granted the area special administrative status and envisioned a referendum in which residents would choose whether to join Sudan or South Sudan. That referendum was never held because the two governments disagreed over voter eligibility, boundaries and the rights of nomadic communities.
Abyei is strategically important because it contains fertile land, grazing routes and oil deposits linked to the Muglad Basin. Both countries continue to claim it, while the area has operated under an interim arrangement rather than a settled international border. The United Nations established UNISFA, the United Nations Interim Security Force for Abyei, in 2011 to help monitor the demilitarized area and protect civilians.
A common mix-up is with Blue Nile or Darfur, which are also tied to Sudanese conflicts but are not the named disputed border region between Sudan and South Sudan.