Between the northern division and the Karlyk-tagh range (or east Tian Shan), there is an undulating barren plain, in altitude and from north to south, sloping downwards from both north and south towards the middle, where lies the oasis of Hami (2,800 ft). Similarly, from the southern division of the Bey-san, a second plain slopes down for to the valley of the river Bulunzir (or Su-lai-ho), which comes out of China, from the south side of the Great Wall, and finally empties itself into the lake of Kalachi (or Kara-nor). From the Bulunzir the same plain continues southwards at a level of to the foot of the Nan-shan Mountains. The total breadth of the desert here, from north to south, is .