42 ASIA 



shrubs, most of which venture to assume their scanty 

 foliage only during the short rainy period. Among 

 them may be recognized familiar denizens of the African 

 semi-deserts, e.g. the Arabian acacia and the tamarix, 

 and along the margins of the dry river-beds, fig-trees and 

 Euphrates poplars. Oases, with palms, are to be found 

 in fair abundance ; but the life of this area is due, 

 and restricted, to the Indus and its tributaries, fed by 

 melting snows of the Himalayas, and dry most of the 

 year. By means of auxiliary canals and irrigation 

 ditches, the productive surface has been extended in the 

 vicinity of the rivers, and wheat can be grown with suc- 

 cess. In short, a parallel may be drawn between this 

 Indus belt and Mesopotamia ; but here the importance of 

 the Himalayan snows is such that the network of rivers 

 and canals allows of a fairly dense human settlement. 



From prehistoric times, the immense wealth and in- 

 finite resources of India have attracted invaders, con- 

 querors, immigrants, adventurers, and travellers, by land 

 and sea, from all points of the compass. In the Deccan, 

 the eastern slopes and plateaus came to be densely 

 peopled, whereas the slopes of the western Ghats, with 

 their dark forests, remained comparatively uninhabited. 

 Geographical changes have also occurred which have 

 moved the centres of population. There was a time 

 when the Indus was a more powerful stream than it 

 now is, and fertilized a much vaster area of its valley. 

 Even the Thar desert is strewn with ruins of forests, 

 canals, and cities, testifying to its former importance. 



Iran is a natural region formed by a vast plateau, 

 defended on all sides by a continuous rim of mountains : 

 on the north by the chain of the Elburz Khorassan 

 merging into the Hindu Kush ; on the east by the 

 broken Baluchistan highlands; on the south and west 



