CHAPTER V.
SOBAT AND YAL BASINS.
HE Sobat, supposed by certain explorers to be the true White Nile, is occasionally even superior in volume to the main stream. It receives the drainage of an extensive basin, roughly estimated at 70,000 square miles. This vast space is still a blank on the map,
or exhibits little more than the names of tribes inserted merely on the authority of the natives and of travellers who have penetrated farthest into the interior. Debono ascended the river in a boat for over 80 miles, while a steamer advanced 140 miles beyond the confluence. Antoine d'Abbadie, Beke, and recently Schuver, have explored several tributary valleys on the western watershed of the Abyssinian highlands, and have, moreover, collected information from the Arab dealers and natives. The Yal, or Jal, which rises in the Anam and Berta highlands under the names of the Yavash or Kishar, that is "Great River," is even less known in its middle and lower course than the Sobat. The Arab traders call it the Sobat, like the much larger river flowing farther south. Its mouth is blocked by sand only during exceptionally dry seasons, such as that of 1861. Between the Yal and the Blue Nile, for the space of more than five degrees of latitude, the White River receives only one perennial affluent. The Nile and its two tributaries are fringed by deleb palms, tamarinds, ebony, and huge acacia forests, which though rich in gum are at present used only for the sake of the wood. One of these acacias is the "coftar" or flute-tree (acacia fistula), whose ivory-like branches are drilled with holes by the insects living in the gall-nuts with which they are covered. The wind rushes through these openings, producing a soft mellow sound like that of the flute. These forests gradually disappear towards the mouth of the Yal, where the bare steppe stretches right and left, relieved only by the smoke of a few Arab camping-grounds.
The Gambil and Koma Tribes.
Most of the inhabitants of the Sobat basin are of Negro stock, the Gallas being met only in comparatively small isolated communities. The first plains watered by the Baro and Garreh affluents on leaving the Abyssinian mountains are occupied
