ere fix their political frontier for a time,
though later they may advance it to the crest of the ridge, in order to
secure a more scientific boundary. The civilized population of the broad
Indus Valley spread westward up the western highlands, only so far as
the shelving slopes of the clay and conglomerate foothills, which
constitute the piedmont of the Suleiman and Kirthar Mountains, afforded
conditions for their crops. Thus from the Arabian Sea for 600 miles
north to the Gomal River, the political frontier of India was defined by
the line of relief dividing the limestone mountains from the alluvial
plain, the marauding Baluch and Afghan hill tribes from the patient
farmers of the Sind.[1190] This line remained the border of India from
pre-British days till the recent annexation of Baluchistan.

These piedmont boundaries are most clearly defined in point of race and
civilization, where superior peoples from the lowlands are found
expanding at the cost of retarded mountain folk. Romans and Rhaetians
once met along a line skirting the foot of the eastern Alps, as Russians
to-day along the base of the Caucasus adjoin the territories of the
heterogeneous tribes occupying that mountain area.[1191] [See map page
225.] The plains-loving Magyars of Hungary have pushed up to the rim of
mountainous Siebenburgen or Transylvania from Arad on the Maros River to
Sziget on the upper Theiss, while the highland region has a predominant
Roumanian population. A clearly defined linguistic and cultural boundary
of Indo-Aryan speech and religion, both Hindu and Mohammedan, follows
the piedmont edges of the Brahmaputra Valley, and separates the lowland
inhabitants from the pagans of Tibeto-Burman speech occupying the
Himalayan slope to the north and the Khasia Mountains to the south. The
highland race is Mongoloid, while the Bengali of an Aryan, Dravidian and
Mongoloid blend fill the river plain.[1192] Such piedmont boundary lines
tend to blur into bands or zones of ethnic intermixture and cultural
assimilation. The western Himalayan foothills show the blend of
Mongoloid and Aryan stocks, where the vigorous Rajputs of the plains
have encroached upon the mountaineer's land.[1193] Of almost every mountain
folk it can be assumed that they once occupied their highlands to the
outermost rim of the piedmont, and retired to the inner rim of this
intermediary slope only under compulsion from without.

[Sidenote: Density of population in piedmont be