iver they met. In the mouth of Persians and Greeks the name was
corrupted into Indus, and then applied to the whole country; but it
still survives in its original form in the local designation of the Sind
province, which comprises the valley of the Indus below the confluence
of the five rivers, which again formed and named the original Punjab.
Significantly enough the western political boundary of the Sind extends
into the barren foothills of Baluchistan only so far as the affluents of
the Indus render the land arable by irrigation; for the Indus performs
for the great province of the Sind, by annual inundation and perennial
irrigation, the same service that the Nile does for Egypt.

The segregation of such districts, and the concentration of their
interests and activities along the central streams have tended to
develop in the population an intense but contracted national
consciousness, and to lend them a distinctive history. Their rivers
become interwoven with their mythology and religion, are gods to be
worshipped or appeased, become goals of pilgrimages, or acquire a
peculiar sanctity. The Nile, Ganges, Jamna, Jordan, Tiber and Po are
such sacred streams, while the Rhine figures in German mythology.

[Sidenote: Rivers as boundaries of races and peoples.]

From the uniting power of rivers it follows that they are poor
boundaries. Only mountains and seas divide sharply enough to form
scientific frontiers. Rivers may serve as political lines of demarcation
and therefore fix political frontiers; but they can never take the place
of natural boundaries. A migrating or expanding people tend always to
occupy both slopes of a river valley. They run their boundary of race or
language across the axis of their river basin, only under exceptional
circumstances along the stream itself. The English-French boundary in
the St. Lawrence Valley crosses the river in a broad transitional zone
of mingled people and speech in and above the city of Montreal. The
French-German linguistic frontier in Switzerland crosses the upper Rhone
Valley just above Sierre, but the whole canton of Valais above the elbow
of the river at Martigny shows fundamental ethnic unity, indicated by
identity of head form, stature and coloring.[692] Where the Elbe flows
through the low plains of North Germany, its whole broad valley is
occupied by a pure Teutonic population--fair, tall, long-headed; a more
brunette type occupies its middle course across the uplands