|Grazing and land rights are key issues for those who live in Abyei [EPA]
Political tensions between north and south Sudan have heightened ahead of a ruling on the disputed borders of Abyei, an oil-producing area claimed by both sides.
Analysts warn that any decision by the permanent court of arbitration in The Hague, which is set to rule on whether the north or the south can lay claim to the region, could spark violence.
What is the dispute about?
The Abyei area is a central region straddling the undefined border between Sudan's mainly Muslim north and the mostly Christian south.
For many years, large parts of the territory have been shared by the Ngok Dinka, part of south Sudan's Dinka tribal group, and the northern Arab Misseriya nomads.
Abyei is currently governed by a joint north-south administration, but residents have been promised a referendum in January 2011 on whether they want to join north or south Sudan.
On the same day, south Sudan as a whole has also been promised a vote on whether to split from north Sudan and form an independent country.
Why are the two sides arguing?
Both sides differ over the ownership of Abyei and its boundaries - the south says Abyei covers a much larger area of land than the north is prepared to accept.
Abyei is also an oil-rich area which neither side would like to lose.
Both want control of oil installations north of Abyei town, run by the Greater Nile Petroleum Operating Company (GNPOC), a consortium led by CNPC of China, the main oil group operating in the Abyei area.
The north could see any loss compounded if the south, as is widely expected, also chooses secession.
Both sides also want to keep the loyalty of communities that supported them during the civil war - for northerners the Misseriya, for southerners the Ngok Dinka.
Abyei has become an emblem for the south and north after decades of fighting and senior members of the south's dominant Sudan People's Liberation Movement (SPLM) come from the area.
What about the people of Abyei?
Grazing and land rights are the key issue for the Dinka and the Misseriya, as both live in the Abyei region.
Many there feel the competition over resources could be managed through traditional settlements and earlier agreements, if the clash had not been escalated to a national level.
How did the dispute end up in The Hague?
The status and borders of Abyei were among the most sensitive issues left undecided in the 2005 Comprehensive Peace Agreement that ended more than two decades of civil war between north and south Sudan.
Efforts to reach a settlement since 2005 have failed and northern and southern forces have already clashed over Abyei a number of times, forcing tens of thousands of civilians to flee.
Clashes over the area left at least 100 people dead in 2008.
Both sides later referred the issue to an Abyei Arbitration Tribunal in The Hague and promised to accept its decision.
What will The Hague court be ruling on?
On the surface, the court's Abyei tribunal has been asked to rule on a technical issue - whether a panel of international experts, set up by the 2005 peace deal, went beyond its mandate when it outlined Abyei's borders.
The Hague tribunal could accept the panel's border, with its northern boundary about 90km north of Abyei town, taking in oilfields, a large section of pipeline, a railway town, grazing land and agricultural projects.
Such a finding would please southerners, although some want even more territory.
If the tribunal decides the panel went too far, it can draw its own boundary.
In the past, northern leaders have argued Abyei makes up a small slice of land south of Abyei town, south of the river Kiir, as it is known by the Dinka, or Bahr el-Arab to northerners.
Under this definition, even Abyei town would fall outside of the Abyei area.
Will there be conflict?
The United Nations, the US and other interested countries, will be pressing both sides to avoid conflict.
But it is unclear where the two sides will find room for compromise - one will probably emerge a winner, the other a loser - and violence is a possibility.
Senior UN and government officials have promised to be in Abyei town on Wednesday to quell any violence.
Ahead of the court's decision, the UN said there has been a build-up of southern troops close to Abyei, an accusation denied by the south.
UN peacekeepers in the town do not have the equipment or manpower to intervene in a full-blown clash.