Pro-government Arab Janjaweed militia have driven over 2m from their homes in the last three years.
In southern Otash camp, women and children collect water early to avoid the blazing rays of the midday sun.
One of the group, Khadmalla Hassan, recalls her recent escape.
“It was midday. The Janjaweed killed seven people. They burnt our houses and we were hiding in the desert for a week. We were very hungry and thirsty. Eventually we saw a truck drive by, which brought us here.”