The basin of the Ghazal is a large one, extending north-west to Darfur, and south-west to the Congo watershed.
Omdurman is the headquarters of the native traders in the Anglo-Egyptian Sudan, the chief articles of commerce being ivory, ostrich feathers and gum arabic from Darfur and Kordofan.
The town and district form a small ethnographical island, having been peopled in the 18th century by a colony of Takruri from Darfur, who, finding the spot a convenient resting-place for their fellow-pilgrims on their way to Mecca and back, obtained permission from the negus of Abyssinia to make a permanent settlement.
Here also is the northern terminus of the caravan route across the desert, which, passing through the Kharga oasis, goes south-west to Darfur.
On it converge various trade routes, notably from Darfur and from Dueim, a town on the White Nile 125 m.