Mountains are seldom equally accessible from all sides. Rarely does the crest of a system divide it symmetrically. This means a steep, difficult approach to the summit from one direction, and a longer, more gradual, and hence easier ascent from the other. It means also in general a wide zone of habitation and food supply on the gentler slope, a better commissary and transport base whence to make the final ascent, whether in conquest, trade or ethnic growth. Mountain boundaries are therefore rarely by nature impartial. They do not umpire the great game of expansion fairly. They lower the bars to the advancing people on one side, and hold them relentlessly in place to the other. To the favored slope they give the strategic advantage of a swift and sudden descent beyond the summit down the opposite side. The political boundary of France along the watershed of the Vosges Mountains is backed by a long, gradual ascent from the Seine lowland and faces a sharp drop to the rift valley of the middle Rhine, Its boundary along the crest of the Alps from Mont Blanc to the Mediterranean brings over two-thirds of the upheaved area within the domain of France, and gives to that country great advantages of approach to the Alpine passes at the expense of Italy. With the exception of the ill-matched conflict between the civilized Romans and the barbarian Gauls, it is a matter of history that from the days of Hannibal to Napoleon III, the campaigns over the Alps from the north have succeeded, while those from the steep-rimmed Po Valley have miscarried. The Brenner route favored alike the Cimbri hordes in 102 B.C. and later the medieval German Emperors invading Italy from the upper Danube. The drop from the Brenner Pass to Munich is 2800 feet; to Rovereto, an equally distant point on the Italian side, the road descends 3770 feet.
Its ethnic effects.
The inequality of slope has ethnic as well as political effects, especially where a latitudinal direction also makes a sharp contrast of climate on the two sides of the mountain system. Except in the Roman period, the southern face of the Alps has been an enclosing wall to the Italians. The southern cultivator penetrated its high but sunny valleys only when forced by poverty, while the harsh climate on the long northern slope effectively repelled him. On the other hand, Switzerland has overstepped the Alpine crest in the province of Ticino and thrust its political boundary in a long wedge down to the lowland of the Po near Como; and the Alpine race, spilling everywhere over the mountain rim into the inviting Po basin, has given to this lowland population a relatively broad skull, blond coloring and tall figure, sharply contrasted with the pure Mediterranean race beyond the crest of the Apennines.[1229]
The long northward slope of the Alps in Switzerland and Tyrol, and the easy western grade toward France, have enabled Germanic and Gallic influences of various kinds to permeate the mountains. A strong element of blond, long-headed Germans mingles in the population of the Aar and Rhine valleys up to the ice-capped ridge of the Glarner and Bernese Alps,[1230] while the virile German speech has pushed yet farther south to the insuperable barrier of the Monte Rosa group. The abrupt southward slope of the Himalayas has repelled ethnic expansion from the river lowlands of northern India, except in the mountain valleys of the Punjab streams and Nepal, where the highland offered asylum to the Rajput race when dislodged by a later Aryan invasion, or when trying their energies in expansion and conquest.[1231] The Tibetan people, whose high plateaus rise almost flush with the Himalayan passes, have everywhere trickled through and given a Mongoloid mountain border to Aryan India,[1232] even though their speech has succumbed to the pervasive Aryan language of the piedmont, and thus confused the real ethnic boundary. [See map page 102.] The retarded and laborious approach of British "influence" up this steep ascent to Lhassa, as opposed to the long established suzerainty of the Chinese Emperor in Tibet, can be attributed in part to the contrasted accessibility from north and south.
Persistence of barrier nature.
Mountains influence the life of their inhabitants and their neighbors fundamentally and variously, but always reveal their barrier nature. For the occupants of one slope they provide an abundant rainfall, hold up the clouds, and rob them of their moisture; to the leeward side they admit dry winds, and only from the melting snow or the precipitation on their summits do they yield a scanty supply of water. The Himalayas are flanked by the teeming population of India and the scattered nomadic tribes of Tibet. Mountains often draw equally clear cut lines of cleavage in temperature. The Scandinavian range concentrates upon Norway the warm, soft air of the Atlantic westerlies, while just below the watershed on the eastern side Sweden feels all the rigor of a sub-Arctic climate. In history, too, mountains play the same part as barriers. They are always a challenge to the energies of man. Their beauty, the charm of the unknown beyond tempts the enterprising spirit; the hardships and dangers of their roads daunt or baffle the mediocre, but by the great ones whose strength is able to dwarf these obstacles is found beyond a prize of victory. Such were Hannibal, Napoleon, Suvaroff, Genghis Khan, and those lesser heroes of the modern work-a-day world who toiled across the Rockies and Sierras in the feverish days of '49, or who faced the snows of Chilkoot Pass for the frozen gold-fields of the Yukon.
Importance of mountain passes.