From hosting refugees from neighbouring states in the 1970s and early 1980s, Sudan has become a generator of forced migration on an unprecedented scale, creating the world’s largest crisis of human displacement. Since 1983, two million Sudanese have died as a result of conflict, about a million have fled to neighbouring countries, and some six million - one sixth of the population - have been displaced within the country.

Before 1989, displacement had been a secondary consequence of conflict. From the late 1980s the deliberate uprooting of local populations became a strategy for the conduct of war involving militia attacks on the ground, burning, looting and the abduction of women and children, coupled with bombardment from the air.

It's estimated fighting between rebel factions has displaced somewhere between 1.5 and 2 million people inside south Sudan. Hopes for resettlement after the January 2005 peace agreement have not been realised as South Sudan is still volatile and devoid of infrastructure. In Darfur, escalating violence continues to threaten the viability of aid operations, and prospects for return are limited. USAID has upwardly revised its figures of the number of affected and at-risk civilians to 2.2 million people.