When northern Sudanese troops seized the disputed border town of Abyei last month, it was a sign that the fragile six-year-old peace between North and South Sudan was teetering on the brink. Some called it the first shots of Sudan's next civil war, following the two-decade-long war that killed an estimated 2 million people.

Like the more well-known conflict in Sudan's western Darfur region, the North-South civil war began as a result of local disputes, a feeling by many southerners that the Islamist-dominated northern government was neglecting its duties to the South. And between the two sides, Abyei rose as a symbolic prize – a Kashmir or a Jerusalem – that must be fought for and defended at all costs.

Now, Abyei could pull the divided nation back into war just weeks before South Sudan officially secedes on July 9.

"It's probably the worst-case scenario," said a United Nations humanitarian worker not authorized to speak on the record.

The UN estimates at least 30,000 have fled Abyei and surrounding villages as a result of recent fighting. According to some local officials, that number is closer to 80,000.

Speaking during a recent trip to Khartoum – the capital of northern Sudan – representatives of the UN Security Council called on the North to withdraw troops from Abyei. But the regime of President Omar al-Bashir – who is wanted by the International Criminal Court for alleged war crimes in Darfur – is digging in its heels. "Abyei belongs to North Sudan," he said emphatically, days after his troops seized Abyei.

"[Mr. Bashir] is doing this because he's looking at the oil we have and [at] our productive land," says Kuei Deng, who fled Abyei with her daughter, daughter-in-law, and several grandchildren. "That's why he's killing us, to make us leave the land. We believe we are southerners. We are Christians. That's why they are doing this."

Officials and experts point out, however, that the North was already awarded oil-rich areas near Abyei in an international border demarcation ruling.

"This is not about oil, because the oil fields are far outside Abyei," says Fouad Hikmat, a Sudan expert at the International Crisis Group in Nairobi, Kenya. "This is about the historical relationships between the Misseriya Arab nomads and the people of Abyei, the Dinka Ngok, and how they share the land. And how years of war have created mistrust between those communities. The road to peace comes through talking with each other, but nobody trusts the other side."

Abyei is a natural border town, geographically and culturally. The local population of town dwellers are farmers and traders of the Dinka Ngok tribe, many of whom have converted to the Christian faith but others have retained their traditional beliefs.

Yet every year in the dry season, nomadic Misseriya Arab herdsmen from the North pass through Abyei on their way south to the marshlands that are south of the river that the Dinka call Kiir and that the Misseriya call Bahar al-Arab.

This pattern of migration has gone on for centuries and is highly formalized, with Misseriya Arab elders working out the timing of their visits to ensure that their cattle don't trample on Dinka crops on their way down south.

The war complicated this relationship, with Misseriya siding with their northern Arab brethren, and with the Dinka seeing themselves as the front lines of southern nationalism. Two decades of war left both sides exhausted, a fact that may be the greatest hope that Sudan can avoid a return to war.

"We will not go back to war. It will not happen," said South Sudanese President Salva Kiir last month. "We are committed to peace."

Yet local grievances, and particularly the grievances in Abyei, still have potential for unleashing horrific violence.

Kuol Arop Kuol, a middle-aged man from Abyei, says he cannot be neighbors with the Misseriya ever again. "We will fight until death and even if South Sudan does not want to help us," he says, tears welling up in his eyes, "because a person without land is not a person."