“The belts between mountain and desert, the banks of the great rivers, the lower hills near the sea, these are the lines of civilization (actual or potential) in Western Asia. The consequence of these conditions is that through all the history of Western Asia there runs the eternal distinction between the civilized cultivators of the plains and lower hills and the wild peoples of mountain and desert. The great monarchies which have arisen here have rarely been effective beyond the limits of cultivation; mountain and desert are another world in which they can get, at best, only precarious footing. And to the monarchical settled peoples the near neighbourhood of this unsubjugated world has been a continual menace. It is a chaotic region out of which may pour upon them at any weakening of the dam hordes of devastators. At the best of times it hampers the government by offering a refuge and recruiting ground to all the enemies of order.” (Bevan: _House of Seleucus_, i., p. 22.) Scornful of agriculture and with a strong distaste for settled and especially for urban life, the Bedwin are those who have remained nomads by preference, and like all races at that stage of evolution, find the most congenial outlet for their vigour in tribal warfare and plundering expeditions. From the earliest dawn of history they have always been strongly tempted by the wealth of the settled communities within reach, and appear in the oldest records as robber bands. Sometimes predatory excursions were followed by settlement, and the invading tribes learned the culture of those amongst whom they settled: all the Semitic groups other than the Arabs had formed such settlements before the 7th century A.D., and these groups are distinguished one from another, and all from the parent stock, simply by the cultural influences due to the earlier inhabitants of the lands they entered; the Arab stock itself remained high and dry, the stranded relic of more primitive conditions, though itself not absolutely free from a reacting influence. The only thing that ever has restrained the incursions of these nomadic tribes into such neighbouring lands as offer hope of plunder is the military power of those who endeavour to place a barrier for the protection of the settled community of the cultivated area, and every Arab outspread has been due, not to the pressure of hunger resulting from the desiccation of Arabia, nor to religious enthusiasm, but simply to the weakness of the power which tried to maintain a dam against them.