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.

[Sidenote: 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.

[Sidenote: Importance of mountain passes.]

For migrating, warring and trading humanity therefore, the interest of
the mountains is centered in the passes. These are only dents or
depressions in the great up-lifted crest, or gaps carved out by streams,
or deeper breaches in the mountain wall; but they point the easiest
pathway to the ultramontane country, and for this reason focus upon
themselves the travel that would cut across the grain of the earth's
wrinkled crust. Their influence reaches far. The B