Sudan and former southern rebels have signed a deal to end a dispute over the oil-rich region of Abyei.
It will allow for the return of tens of thousands of people who fled fighting there last month.
President Omar al-Beshir signed the agreement with former rebel leader and First Vice President Salva Kiir in Khartoum late yesterday.
Besides allowing for the return of those displaced by fighting in the central region last month, the agreement includes setting up an interim administration and seeking international arbitration to resolve the dispute.
So-called Joint Integrated Units made up of troops from north and south are to deploy in the area within 10 days.
Fighting in Abyei had threatened a return to Sudan's two-decade civil war - the longest in Africa - which only ended with the signing of the Comprehensive Peace Agreement in 2005.
Under the 2005 deal, the south was offered a six-year transition period of regional autonomy and participation in a unity government until a 2011 referendum on self-determination.
Halfway through the transition period, Abyei is still not governed by a functioning joint administration as stipulated.
The impasse has been one issue delaying implementation of the entire peace deal.
The deal ended the civil war between north and south Sudan in which more than 1.5m people were killed.
UN officials warn that up to 90,000 people may have been displaced by two rounds of fighting in May between government soldiers and the southern Sudan People's Liberation Army that flattened Abyei's main town.
The ethnic clash in Abyei is between the Ngok Dinka generally affiliated to the south who dominated the town and outlying villages, and nomadic Arab tribesmen who migrate seasonally to graze their animals.
