The Gash enters the Sudan near Kassala and north of that town turns west towards the Atbara, but its waters are dissipated before that river is reached.
East of the Nile the region of absolute desert ceases about the point of the Atbara confluence.
The country enclosed by the Nile, the Atbara and the Blue Nile, the so-called Island of Mero, consists of very fertile soil, and along the eastern frontier, by the upper courses of the rivers named, is a district of rich land alternating with prairies and open forests.
The Jaalin, Hassania and Shukria inhabit the country between the Atbara and Blue Nile; the Hassania and Hassanat are found chiefly in the Gezira.
Kassala is on the river Gash east of the Atbara and near the Eritrean frontier.