CHAPTER VIII.
UPPER NUBIA.
HE whole of the northern and western watershed of Abyssinia, with the exception of the basin watered by the Barka, is known by its hydrography to belong to the Nilotic system. The region watered by the Blue Nile and the Atbara, with their affluents, is geographically sharply defined westwards by the Bahr-el-Abiad, or Great Nile, and eastwards by the advanced promontories of the Abyssinian plateau. To the south the water-parting between the Tumat, a tributary of the Blue Nile, and the Sobat, one of the main branches of the White Nile, is partly composed of mountains or high hills which have not yet been crossed by European explorers. An unknown land, with an area equal to that of Belgium and Holland together, stretches beyond these limits, and here the frontiers are more effectually guarded by its savage, warlike, or wandering peoples than by a line of fortresses and custom-houses. The zone of separation between Upper and Lower Nubia is formed by the relatively small region which separates the Nile at its junction with the Atbara from the waters flowing to the Red Sea. With these boundaries the whole of the plains between the Nile and Abyssinia constitute the region of Nubia, usually designated under the name of Eastern Sudan, although the term of Beled-es-Sudan, or "Land of the Blacks," should be restricted to lands inhabited by Negroes. The total superficial area of this region may be approximately estimated at 224,000 square miles; the population of the whole territory, extremely dense in the basins of the Tumat and Jabus, may perhaps number 3,000,000.
Physical and Poltical Features.
Forming a distinct domain to which the general slope of the soil gives a certain geographical unity, eastern Sudan consists of distinct basins verging slightly north-. westwards along the Blue Nile and Atbara, and diverging northwards along the Mareb and Barka. It is cut up by isolated masses on the plains, by chains of hills and desert spaces, into natural provinces which the tribes engaged in war have converted into so many petty states, whose frontiers are changed according to the fortune of war and the constant inroads of the nomad peoples. The more scanty
