Sudan, in Mud Brick and Marble

In Sudan, successive rebel movements -- first in the south and now in Darfur -- have voiced similar grievances against the government. The ruling party in Khartoum, they say, hoards power and wealth at the expense of the rest of the country, physically the largest in Africa.

And in the past several years, the new oil wealth and investment pouring into the city of 6 million have sharpened the contrast between center and periphery.

These days, Khartoum has palm trees wrapped in lights, new Toyota dealerships and an outdoor cafe where patrons can sip lattes under a delicately refreshing mist spray. This week marks the opening of Khartoum's first five-star hotel, Al Salam Rotana -- a swank, $300-a-night palace of marble and haute cuisine for the jet set.

At the city's edges, however, is the detritus of power struggles dating back decades -- a dozen or so squalid, off-the-map camps, most without running water or electricity, and filled with more than 2 million people. Most of the residents are non-Arab Africans who fled the conflict in the south. More recently, people have come here to escape the conflict in Darfur, now in its fourth year.

For people in the camps, the economic boom has had the perverse effect of further undermining their already precarious existence. With land at a premium, the local government of Khartoum state periodically sends police and bulldozers into the camps to plow under swaths of mud houses, pushing people even farther out into the desert, and then sells the cleared land to developers.

The technique, called kasha, was first used by the government in the mid-1980s to force out southerners who had fled the civil war. The current ruling party has "perfected" the technique, said Alfred Taban, editor in chief of the Khartoum Monitor newspaper and a frequent critic of the government.

Since the conflict in Darfur began, as many as 450,000 people have died there from disease and violence and 2.5 million have fled to camps in the area or across the border in Chad.

In recent months, the humanitarian situation in Darfur has worsened, as aid workers have been targeted in the violence and many relief groups have pulled out, leaving hundreds of thousands of people without food, medicine or clean water. President Omar Hassan al-Bashir has consistently rejected a proposal to send in a force of several thousand United Nations peacekeepers to supplement a beleaguered African Union force of 7,000 troops currently deployed in Darfur.

Meanwhile, the peace agreement in the south is faltering, with southern Sudanese officials accusing the government of shortchanging them on oil revenue and failing to implement power-sharing arrangements.

Increasingly, leaders in the south say the fate of their region is very much intertwined with that of Darfur, a notion that hearkens back to the vision of John Garang, the widely popular and iconic leader of the Sudan People's Liberation Movement (SPLM) who died in a helicopter crash in 2005.

Under his leadership, the SPLM had strong ties to rebel groups not only in Darfur, but also in the north and the east, as Garang came to realize that the suffering extended beyond his own region and that the only way to achieve a more just order in Sudan was through a unified movement. After his death, those relationships languished.

In recent weeks, however, the current president of southern Sudan, Salva Kiir Mayardit, has been reaching out to Darfur rebel leaders.

"We have similar grievances," said Deng Alor Kuol, a southerner who became a minister in the national government after the 2005 peace agreement. "Marginalization and neglect."