cted
importance.[653]

The control of a river mouth becomes a desideratum or necessity to the
upstream people. Otherwise they may be bottled up. Though history shows
us countless instances of upstream expansion, nevertheless owing to the
ease of downstream navigation and this increasing historical importance
from source to mouth, the direction of a river's flow has often
determined the course of commerce and of political expansion.

[Sidenote: Location at hydrographic centers.]

The possibility of radial expansion, which we have found to be the chief
advantage of a central location, is greatly enhanced if that central
location coincides with a hydrographic center of low relief. The tenth
century nucleus of the Russian Empire was found about the low nodal
watershed formed by the Valdai Hills, whence radiated the rivers later
embodied in the Muscovite domain. Here In Novgorod at the head of the
Volchov-Ladoga-Neva system, Pskof on the Velikaya, Tver at the head of
the navigable Volga, Moscow on the Oka, Smolensk on the Dnieper, and
Vitebsk on the Duna, were gathered the Russians destined to displace the
primitive Finnish population and appropriate the wide plains of eastern
Europe. Everywhere their conquests, colonization, and commercial
relations have followed the downstream course of their rivers. The
Dnieper carried the Rus of Smolensk and Kief to the Euxine, into contact
with the Byzantine world, and brought thence religion, art, and
architecture for the untutored empire of the north. The influence of the
Volga has been irresistible. Down its current Novgorod traders in the
twelfth century sought the commerce of the Caspian and the Orient; and
later the Muscovite princes pushed their conquest of the Tartar hordes
from Asia. The Northern Dwina, Onega, Mesen and Petchora have carried
long narrow bands of Slav settlement northward to the Arctic Ocean. [See
map page 225.] Medieval Russian trade from Hanseatic Pskof and Novgorod,
and later Russian dominion followed the Narva and Neva to the Baltic.
"The Dnieper made Russia Byzantine, the Volga made It Asiatic. It was
for the Neva to make it European."[654]

In the same way, when the early French explorers and traders of Canada
reached the hydrographic center of the continent about Lakes Superior
and Michigan, they quickly crossed the low rim of these basins southward
to the Mississippi, and northward to the Rainy Lake and Winnipeg system
draining to Hudson Bay.[655] Wh