Members of Sudan's Nuba community wearing tribal outfits take part in the Nuba Mountains Cultural Heritage Festival, marking the International Day of the World's Indigenous Peoples, on August 15, 2015, in the capital's twin city of Omdurman. The Nuba hail from South Kordofan state's Nuba Mountains but thousands have migrated to Khartoum, fleeing conflict and poverty in their long-marginalised region. AFP PHOTO / ASHRAF SHAZLY