not large enough to cope with
them. Again and again during the thirteenth and fourteenth centuries
Tartar hordes swept over the country--burning the villages and towns,
and spreading devastation wherever they appeared--and during more than
two centuries Russia had to pay a heavy tribute to the Khans.

Gradually the Tsars threw off this galling yoke. Ivan the Terrible
annexed the three Khanates of the Lower Volga--Kazan, Kipttchak, and
Astrakhan--and in that way removed the danger of a foreign domination.
But permanent protection was not thereby secured to the outlying
provinces. The nomadic tribes living near the frontier continued their
raids, and in the slave markets of the Crimea the living merchandise was
supplied by Russia and Poland.

To protect an open frontier against the incursions of nomadic tribes
three methods are possible: the construction of a great wall, the
establishment of a strong military cordon, and the permanent subjugation
of the marauders. The first of these expedients, adopted by the Romans
in Britain and by the Chinese on their northwestern frontier, is
enormously expensive, and was utterly impossible in a country like
Southern Russia, where there is no stone for building purposes; the
second was constantly tried, and constantly found wanting; the third
alone proved practicable and efficient. Though the Government has
long since recognised that the acquisition of barren, thinly populated
steppes is a burden rather than an advantage, it has been induced to go
on making annexations for the purpose of self-defence, as well as for
other reasons.

In consequence of this active part which the Government took in the
extension of the territory, the process of political expansion sometimes
got greatly ahead of the colonisation. After the Turkish wars and
consequent annexations in the time of Catherine II., for example, a
great part of Southern Russia was almost uninhabited, and the deficiency
had to be corrected, as we have seen, by organised emigration. At the
present day, in the Asiatic provinces, there are still immense tracts of
unoccupied land, some of which are being gradually colonised.

If we turn now from the East to the West we shall find that the
expansion in this direction was of an entirely different kind. The
country lying to the westward of the early Russo-Slavonian settlements
had a poor soil and a comparatively dense population, and consequently
held out little inducement to emigrati