Farther east, towards the Balkan Peninsula, the expansive tendency is much more complicated and of very ancient date.  The Russo-Slavs who held the valley of the Dnieper from the ninth to the thirteenth century belonged to those numerous frontier tribes which the tottering Byzantine Empires attempted to ward off by diplomacy and rich gifts, and by giving to the troublesome chiefs, on condition of their accepting Christianity, princesses of the Imperial family as brides.  Vladimir, Prince of Kief, now recognised as a Saint by the Russian Church, accepted Christianity in this way (A.  D. 988), and his subjects followed his example.  Russia thus became ecclesiastically a part of the Patriarchate of Constantinople, and the people learned to regard Tsargrad—­that is, the City of the Tsar, as the Byzantine Emperor was then called—­with peculiar veneration.

All through the long Tartar domination, when the nomadic hordes held the valley of the Dnieper and formed a barrier between Russia and the Balkan Peninsula, the capital of the Greek Orthodox world was remembered and venerated by the Russian people, and in the fifteenth century it acquired in their eyes a new significance.  At that time the relative positions of Constantinople and Moscow were changed.  Constantinople fell under the power of the Mahometan Turks, whilst Moscow threw off the yoke of the Mahometan Tartars, the northern representatives of the Turkish race.  The Grand Prince of Moscow thereby became the Protector of the Faith, and in some sort the successor of the Byzantine Tsars.  To strengthen this claim, Ivan III. married a niece of the last Byzantine Emperor, and his successors went further in the same direction by assuming the title of Tsar, and inventing a fable about their ancestor Rurik having been a descendant of Caesar Augustus.

All this would seem to a lawyer, or even to a diplomatist, a very shadowy title, and none of the Russian monarchs—­except perhaps Catherine II., who conceived the project of resuscitating the Byzantine Empire, and caused one of her grandsons to learn modern Greek, in view of possible contingencies—­ever thought seriously of claiming the imaginary heritage; but the idea that the Tsars ought to reign in Tsargrad, and that St. Sophia, polluted by Moslem abominations, should be restored to the Orthodox Christians, struck deep root in the minds of the Russian people, and is still by no means extinct.  As soon as serious disturbances break out in the East the peasantry begin to think that perhaps the time has come for undertaking a crusade for the recovery of the Holy City on the Bosphorus, and for the liberation of their brethren in the faith who groan under Turkish bondage.