This systematic movement of nomads within their accepted boundaries leads, on slight provocation, to excursions beyond their own frontiers into neighboring territories.  The growing herd alone necessitates the absorption of more land, more water-holes, because the grazed pastures renew their grass slowly under the prevailing conditions of drought.  An area sufficient for the support of the tribe is inadequate for the sustenance of the herd, whose increase is a perennial expansive force.  Soon the pastures become filled with the feeding flocks, and then herdsmen and herds spill over into other fields.  Often a season of unusual drought, reducing the existing herbage which is scarcely adequate at best, gives rise to those irregular, temporary expansions which enlarge the geographical horizon of the horde, and eventuate in widespread conquest.  Such incursions, like the seasonal movements of nomads, result from the helpless dependence of shepherd tribes upon variations of rainfall.

The nomad’s basis of life is at best precarious.  He and want are familiar friends.  A pest among his herds, diminished pasturage, failing wells, all bring him face to face with famine, and drive him to robbery and pillage.[1071] Marauding tendencies are ingrained in all dwellers of the deserts and steppes.[1072] Since the days of Job, the Bedouins of Arabia have been a race of marauders; they have reduced robbery to a system.  Predatory excursions figure conspicuously in the history of all the tribes.  Robber is a title of honor.[1073] Pliny said that the Arabs were equally addicted to theft and trade.  They pillaged caravans and held them for ransom, or gave them safe conduct across the desert for a price.  Formerly the Turkoman tribes of the Trans-Caspian steppes levied on the bordering districts, notably the northern part of Khorasan, which belonged more to the Turkomans, Yomut and Goklan tribes of the adjoining steppe than to the resident Persians.  The border districts of Herat, Khiva, Merv and Bukhara used to suffer in the same way from the raids of the Tekkes, till the Russians checked the evil.[1074] The Tekkes had depopulated whole districts, invaded Persian towns of considerable size, and carried off countless families into slavery.  Both Turkomans and Kirghis tribes prior to 1873 raided caravans and carried off the travelers to the slave markets of Bukhara and Samarkand.[1075] [See map page 103.]

Among these tribes no young man commanded respect in his community till he had participated in a baranta or cattle-raising.[1076] For centuries the nomadic hordes of the Russian steppes systematically pillaged the peaceful agricultural Slavs, who were threatening to encroach upon their pasture lands.  The sudden, swift descent and swift retreat of the mounted marauders with the booty into the pathless grasslands, whither pursuit was dangerous, their tendency to rob and conquer but never to colonize, involved Russia in a long struggle, which ceased only with the extension of Muscovite dominion over the steppes.[1077]