Link Relations of Southwestern Asia 261 



be heard, the same tents seen, and the 

 same tribal customs studied under the 

 scattered and isolated conditions of no- 

 madic life. 



FLORA BOUNDING CULTURE REGIONS 



The flora of a region, which is a blend 

 of the influences of its physiography, 

 its precipitation, and its climate,. makes 

 these relations still more clear. The flora 

 also, since its limits define the bounds of 

 agriculture, constitutes sharper bound- 

 aries for varying culture than are fur- 



nished by any other physical condition. 

 While the climate and precipitation of 

 the Mediterranean, the north African, 

 and the southwestern Asian region vary, 

 the same flora extends from the western 

 flanks of the valley of the Indus to the 

 Pillars of Hercules. Essentially the 

 same flowering plants flourish from the 

 southern edge of the Pyrenees, Alps, 

 and the Julian chain to the southern 

 edge of the Atlas, and the more favored 

 Saharan oases. Substantially the same 

 genera, with far smaller variations also 

 in species than would be anticipated, 



