Up to the twelfth century, Russian life was concentrated in the splendid and prosperous centre of Kiev; but in the thirteenth century came a crushing blow which was destined to set back the clock of Russian culture for three hundred years, namely, the Tartar invasion. Kiev was destroyed in 1240. After this, the South was abandoned; Lithuania and Poland became entirely separated from the East; the Eastern principalities centred round Moscow; the Metropolitan of Kiev transferred his see to Moscow in 1328; and by the fourteenth century Moscow had taken the place of Kiev, and had become the kernel of Russian life and culture. Russia under the dominion of the Tartar yoke was intellectually stagnant. The Church alone retained its independence, and when Constantinople fell, Moscow declared itself to be the third and last Rome: but the independence of the Church, although it kept national feeling alive under the Tartar yoke, made for stagnation rather than progress, and the barrier between Russia and the culture of the West was now solid and visible. From the fourteenth century until the beginning of the nineteenth century, Russian literature, instead of being a panorama of various and equally splendid periods of production, such as the Elizabethan epoch, the Jacobean epoch, and the Georgian epoch, or, as in France, the Renaissance, the _Grand Siècle_, and the philosophic era of the eighteenth century, has nothing to show at all to the outward world; for during all this time the soil from which it was to grow was merely being prepared, and gradually, with difficulty and delay, gaining access to such influences as would make any growth possible. All that is important, as far as literature is concerned, in this period, are those events and factors which had the effect of making breaches in the wall which shut Russia off from the rest of Europe; in letting in that light which was necessary for any literary plants to grow, and in removing those obstacles which prevented Russia from enjoying her rightful heritage among the rest of her sister European nations: a heritage which she had well employed in earlier days, and which she had lost for a time owing to the barbarian invasion. The first event which made a breach in the wall was the marriage of Ivan III, Tsar of Moscow, to Sophia Palæologa, the niece of the last of the Byzantine Emperors. She brought with her Italian architects and other foreigners, and the work of Peter the Great, of opening a window in Russia on to Europe, was begun.