[Sidenote:  Historical results of mountain raiding.]

These depredations reflect to a great degree the complementary relation of highlands and lowlands.  The plains possess what the mountains lack.  This is a fundamental fact of economic geography, and inevitably leads to historical results.  The marauding expeditions of mountain peoples first acquire historical importance, either when the raids after long continuance end in the conquest of the lowlands, and thus augment the resources and population of the highland state; or, as is often the case, the raiders call down upon themselves the vengeance of the plainsmen, are subdued, and embodied in the lowland state.  The conquest of ancient Assyria and the destruction of Nineveh by the mountain Medes seems to have been a process of this kind.  Long before their descent upon Mesopotamia, they were known as the “dangerous Medes,” were constantly threatening the Assyrian frontiers and occupying isolated tracts.[1372] The predatory incursions of the Samnites of the Apennines into the fertile fields of Campania eventuated in the conquest of ancient Capua and other cities, and greatly strengthened the Samnite Confederacy.  But this encroachment of the mountain tribes upon the plains aroused the cupidity and alarm of the Romans, who in turn bent their energies toward the final subjugation of the Samnites.[1373] Himalayan Nepal, after the unification of its petty Rajah states by the Gurkha conquest between 1768 and 1790, began encroachments and ravages upon the Indian Terai or fertile alluvial lowland at the foot of the mountains; and finally by 1858 had acquired title to a considerable strip of it, which by its rice fields and forests greatly strengthened the geographic and economic base of the highland state.[1374] The Malay Hovas, inhabiting the central plateau of Madagascar, braced to effort by its temperate climate and not over-generous soil, have almost everywhere subdued the better fed but sluggish lowlanders of the coast.[1375] There can be little doubt that the beneficent effects of an invigorating mountain climate, especially in tropical and subtropical latitudes, have helped the hardy, active hill people to make easy conquest of the enervated plainsmen.

[Sidenote:  Conquest of mountain regions]

It is more often the case, however, that the scant resources, small number, and divided political condition of the mountain tribes make such conquest impossible.  Their depredations provoke reprisals from the stronger states of the plain, who bring the mountain region under subjection, merely to police their frontier.  Strabo makes it clear that the Romans, having secured certain passes over the Alps, neglected the conquest of the ranges, till the increase of Roman colonies along the piedmont rim excited the cupidity of the mountaineers.  Muscovite dominion was extended over the Caucasus, both in order to check the persistent raids of its tribes into the Russian plains, and to