to the upper Oka in the N.E., is the most important.
By 1560 all the Finnic and Tatar tribes between the Oka and the Kama had become Russian subjects.
of a line drawn from the Niemen to the upper Oka and Don, and thence N.E.
by plains below 300 ft., which join the depression of the middle Volga, and extend as far as the mouth of the Oka.
Dvina, the Dnieper, and even the Lovat and the Oka, take their rise (in the N.W.