X vi INTRODUCTION. 
caravan-routes of great antiquity, and as it has been frequently crossed by modern 
explorers and recently by newspaper correspondents, its physical characters are well 
known, but not so those of the country lying immediately to the north of it. The 
distance between the towns of Berber and Suakin is about 500 kilom. In the 
neighbourhood of Berber or El Mekheref, 350 metres above the sea-level, there is 
more or less cultivation, but the extent to which it is carried on depends entirely on the 
rainfall. A few miles beyond the town the route passes the Wells of Mahobeh, where 
there are a few trees and some scanty vegetation, and proceeding onwards crosses 
Wadi Selem, which is occasionally an unbroken field of sorghum, but in unfavourable 
seasons a mere sterile plain with straggling tufts of dry yellow grass. The route 
traverses a dreary sandy plain covered more or less with loose black rocks, some of 
them standing erect, one more prominent than the others being a well-recognized land- 
mark about 11 metres high, and known to the natives as Abu Odfa, but its base is 
being slowly eaten away by the incessant sand-drift. The plain rises very gradually to 
the east, and when nearly 96 kilom. from Berber have been accomplished, the famous 
shifcing sand-dunes of O Bak are reached, enclosing a series of wells, in the neighbour- 
hood of which there is a scanty vegetation, and occasionally, after rain, a crop of 
sorghum is raised by the wandering Bisharin families frequenting the place. Beyond 
O Bak, the route crosses the broad plain of Wadi Laemeb that supports a little herbage 
of coarse grass. The main or northern route continues to ascend, and crossing a 
number of rocky ridges descends into the valley of Ariab, with its wells of excellent 
water. This valley is about 8 kilom. long and 3 to 4 kilom. in breadth, and is distant 
about 180 kilom. from Berber, and lies at an elevation of nearly 54S metres above 
the sea. It is covered rather thickly, for a valley of this region, with acacias and coarse 
o-rass, which afford a plentiful supply of food for the herds of goats, sheep, and camels 
owned by the nomads who frequent it. Trees in this valley are rare, but the hollow 
trunk of one in the neighbourhood of the wells is large enough to give shelter to a 
man. There are no permanent streams in this valley, neither in any of the other 
numerous khors and wadis of this mountain-range, but occasional storms break over it 
and dew falls at night in winter. Beyond this, low granite hills are passed, and 
then the traveller enters the narrow Wadi Yumga, and again passing rocky hills, 
traverses a broad level rocky plain surrounded by mountains to enter the Wadi Kokreb. 
This part of the country does not merit the term desert, as it consists of a succession 
of deep valleys more or less characterized by the existence of good pasture and a few 
trees that afford shade, some of the plains even boasting of a fairly rich vegetation. 
The khors in this neighbourhood teem with animal and vegetable life, gazelles and 
hares being common. Beyond Wadi Kokreb the road ascends a spur over 700 metres 
high above the sea, and enters the Wadi Ohabdl, 8 kilom. in length, closed in by hills, 
treeless, and strewn with fragments of porphyry and greenstone. The upper end of 
this wadi opens on a broad barren plain covered with fragments of rock, but its dry 
