The wide plains, intersected by far-winding rivers, offered no obvious barriers which might have marked off a separate kingdom of Tchernigov or Polotzk, and each district was too dependent on the others to become permanently estranged. The other factor which made for unity was the bond of a common, and as regards their western neighbours, a distinct religion. The Greek-Christian faith, with all its attendant ceremonials and mysteries, had taken deep root among the Slavs of Russia, and had assimilated itself with the national life of the people. The beauties of the old cathedrals of S. Sofia at Kiev, S. John Theologus at Rostov, and S. Dimitri at Vladimir, bore evidence of the care that was lavished on the decoration of these temples of Christian worship. The Metropolitan of Kiev, as Primate over all the Russian churches, served as a link with the capital city which the Grand Prince did not always supply. Novgorod, which has been mentioned as an exception to the state of subserviency prevalent among the other Russian towns, derived her strength and importance from her situation, which commanded both the Baltic and the Russian overland trade. Although the Hansa League had not yet taken definite shape, the elements of the later organisation were already in existence. The commercial life of the Baltic centred in Wisby, capital of the island of Gothland, and to this convenient meeting-place came, twice a year, German, Swedish, Russian, Danish, and Wendish merchants to exchange their various wares and supply the needs of their respective trade-circles. After the Wisby markets were over many of the traders from Lubeck, Hamburg, Bremen, etc., made their way to Novgorod, where they early possessed a factory and a separate place of worship, even as the Novgorodskie, since the middle of the twelfth century, had their church and quarter at Wisby. The intercourse with enterprising merchant folk from other lands--and merchants needed to be adventurous in those days--infused a spirit of energy and independence into the inhabitants of Novgorod, while the wealth at their disposal enabled them to extend their domination far over the bleak, but by no means barren, northlands of Russia, even to the further side of the Ourals. This extensive over-lordship, again, gave them control of many sources of commerce, and the produce of Arctic seas and sub-Arctic forests filtered through their hands into the channels of Baltic trade. Walrus teeth, the blubber oil from seals, and the down of sea-haunting birds formed the harvest of the frozen ocean; forest and lake furnished their markets with furs, raw leather, tallow, fish, and tar; cultivated lands yielded flax and hemp, honey and wax--the latter an important commodity in the times when the Church kept tapers burning day and night in thousands of shrines throughout the greater part of Europe. In exchange for these products the merchants of Wisby and of the German