Projects: South Sudan

In early 2005, Sudan's government and rebels from the south officially ended Africa's longest-running war. The 21-year civil conflict killed 2 million people and forced more than 4 million from their homes, according to U.N. estimates.

-Under peace deal, oil revenues to be shared. -Refugees started returning in December 2005-Aid workers cite ongoing violence

Under international pressure, the country's ruling party agreed to split Sudan's massive oil revenues with a southern government led by the Sudanese People's Liberation Movement (SPLM), the main rebel group in the south. But some analysts say the agreement is fraught with problems, and getting the south back on its feet is likely to take years, as well as billions of aid dollars. Meanwhile, one of the world's most overlooked humanitarian emergencies continues to fester.

A separate conflict in Sudan's western Darfur region and a smaller but potentially explosive conflict in the east threaten to derail the whole peace process. Conversely, without a lasting peace between north and south Sudan, there is unlikely to be a resolution to the Darfur conflict.