The International Organization for Migration has just released a thorough study on Sudan titled “Migration in Sudan: A Country Profile 2011” (PDF).
The population of Sudan, according to the 2008 census, reached almost 40 million people and consists of more than 150 ethnic groups. In the past three decades there was a massive movement of persons, especially young males, from the South to more developed and resource rich areas in Khartoum, Al-Gadarif, Southern Darfur and Red Sea regions.
Although many southerners returned to the south following the 2005 Comprehensive Peace Agreement, there were new displacements in Darfur where more than 50 percent of the population moved. As a result, Sudan and Columbia now have the highest number of internally displaced persons in the world.
The foreign born population in Sudan was estimated at 750,000 in 2010. About 685,000 of this number are refugees mostly from Eritrea, Chad and Ethiopia. The refugee population has declined by about half in the last 20 years due to voluntary and organized repatriations. Sudan also has a sizable number of economic migrants from neighboring countries, China, India, Philippines and Turkey.