Genghis Khan.[394] Similarly, semi-independent military communities for
centuries made a continuous line of barriers against the raids of the
steppe nomads along the southern and southeastern frontiers of Russia,
from the Dnieper to the Ural rivers. There were the "Free Cossacks,"
located on the debatable ground between the fortified frontier of the
agricultural steppe and marauding Crimean Tartars. Nominally subjects of
the Czar, they obeyed him when it suited them, and on provocation rose
in open revolt. The Cossacks of the Dnieper, who to the middle of the
seventeenth century formed Poland's border defence against Tartar
invasion, were jealous of any interference with their freedom. They lent
their services on occasions to the Sultan of Turkey, and even to the
Crimean Khan; and finally, in 1681, attached themselves and their
territory to Russia.[395] Here speaks that spirit of defection which is
the natural product of the remoteness and independence of frontier life.
The Russians also attached to themselves the Kalmucks located between
the lower Volga and Don, and used them as a frontier defence against
their Tartar and Kirghis neighbors.[396] In this case, as in that of the
Cossacks and the Charkars of eastern Mongolia, we have a large body of
men living in the same arid grassland, leading the same pastoral life,
and carrying on the same kind of warfare as the nomadic marauders whose
pillaging, cattle-lifting raids they aim to suppress. The imperial
orders to the Charkars limit them strictly to the life of herdmen, with
the purpose of maintaining their mobility and military efficiency. So in
olden times, for the Don Cossacks agriculture was prohibited on pain of
death, lest they should lose their taste for the live-stock booty of a
punitive raid. A still earlier instance of this utilization of border
nomads is found in the first century after Christ, when the Romans made
the Arabian tribe of Beni Jafre, dwelling on the frontier of Syria, the
warders of the eastern marches of the Empire.[397]

[Sidenote: Lawless citizens deported to frontiers.]

The advancing frontier of an expanding people often carries them into a
sparsely settled country where the unruly members of society can with
advantage be utilized as colonists. After centralized and civilized
Russia began to encroach with the plow upon the pastures of the steppe
Cossacks, and finally suppressed these military republics, the more
turbulent and obstinate remna