THE CHINO-THIBETAN BORDERLAND 151 



It is a region where altitude and climate, rather than longi- 

 tude and latitude, define the frontiers. In the north-west the 

 highlands of Central Asia abut more closely on the Red Basin 

 than they do in the south-west, and form uplands suitable as 

 grazing-grounds for herds of yak, cattle, horses, and sheep. 

 These areas are peopled by nomadic Thibetans, with whom 

 agriculture is relatively unimportant. The broken country, 

 made up of mountain-crag and valley, which forms the greater 

 part of this hinterland, is occupied by various tribes, with 

 whom agriculture is the paramount industry, and wheat, 

 barley, and bucksvheat the staple food-stuffs. The forests of 

 this region contain much game, of which these people are skilled 

 hunters. Lastly, in the more fertile valleys, where rice and 

 maize can be successfully grown, Chinese settlers are found, but, 

 as mentioned earlier, away from trading-centres and the great 

 highway between Chengtu and Tachienlu, they are not much 

 in evidence 



In the first chapter brief reference to the mountain chains 

 and rivers of this region has been made, but perhaps a few of 

 the more striking features may be given in detail here. Unlike 

 the mountains bordering the eastern limits of the Red Basin, 

 which are mainly of hard Carboniferous and Ordovician lime- 

 stones, those of the west are principally of mudshalesand granitic 

 rocks. Here and there, for example Mount Omei and its sister 

 mountains Wa and Wa-wu, hard limestones have been forced 

 up through the older rocks and form bold peaks and stupendous 

 precipices. There is indeed plenty of limestone throughout 

 the hinterland, but Pre-Cambrian rocks preponderate enor- 

 mously. These and the shales (probably Silurian) disinte- 

 grate very readily in their exposed parts and erosion is rapid. 

 In the deforested parts landslides are general. The region is 

 fairly rich in gold, silver, copper, lead, iron, and other minerals, 

 but very little mining is carried on. Coal is very rare, except 

 in a few localities where limestone predominates, as near Mount 

 Omei and the surrounding region. Salt is known from one 

 locality only (Pai-yen-ching in the Chiench'ang Valley). Around 

 Tachienlu hot springs of calcareous and chalybeate waters, 

 more or less rich in sulphur, are common. These springs are 

 usually found in close proximity to torrents, very often occur- 



