South of Wadi Baaneit the plain is crossed by many drainage channels coursing north-east to join Wadi Shab, and the plain is covered here with quite a park-like growth of acacia trees. The principal channel, which comes from the hills about four kilometres south Bir Baaneit, is called =Wadi Kilanai=. A little south of Wadi Kilanai the plain cuts far back to the west, and the drainage entering this portion comes from the heart of the Gerf mountains to the north-west. A large isolated granite hill-mass called Kilia Arib and numerous smaller hills break the monotony of the plain and cause much branching and looping of the drainage channels. The principal artery draining the south parts of Gebel Gerf is the =Wadi Diqdib=, which originates on the south flanks of the highest peaks, right in the heart of the mountain mass. In one of the heads is a well called =Bir Diqdib=, which, though of great service to the Koatil Arabs who inhabit this district with their camels and other animals, is of little importance to the traveller because of its situation in a closed-in wadi and thus not being on any route. From its head, Wadi Diqdib courses south-westward for fifteen kilometres or more among the mountains, receiving many feeders, before it emerges on to the plain. On leaving the mountains it splits up, part of its drainage going round by the north side of Kilia Arib, and part by the south, in each case by a number of anastomosing channels. The =Wadi Um Saha= drains the hills south-west of Bir Baaneit, and after coursing southwards among the mountains turns the corner and runs north-east across the plain to Wadi Shab. =Wadi Sherefa el Sharqi=, which drains the south portion of the Gerf _massif_ and the north-east flanks of Gebel Dreb, heads in the important Sherefa pass, 807 metres above sea-level, and forming the direct route from Gebel Hamra Dom and Gebel Um Rasein to Bir Sararat Seyet by way of Wadi Sherefa el Gharbi. The pass is a fairly easy one, though the fall is rapid, especially on the east side, where Wadi Sherefa el Sharqi falls no less than one hundred metres in the first two kilometres of its course. A feeder which enters Wadi Sherefa el Sharqi from the south about two kilometres below the pass is said to lead by another pass to a well called =Bir Bint el Dreb=, situated at the head of =Wadi Dreb=, a tributary of Wadi Feqoh. For the first seven kilometres of its east-south-easterly course below the pass, Sherefa el Sharqi is shut in by very high hills, from which numerous feeders join it; it then divides just before reaching the great white granite hills called Eir Arib, part of its drainage going southward to join Kwat Hewah, and part continuing its course on the north side of the granite hills to join Diqdib near the granite cones of Tibashoi and thence turning northwards over a large sandy plain to enter Wadi Shab.