The ancient Kingdom of Kiev, which is called “Old [178]Russian” in all historical works, was a state organized by the southern group of the Eastern Slavic races, particularly the Polan race around Kiev. The tribal chiefs, who had grown rich thru commercial relations with Byzantium, founded the State of Kiev. This government was already in existence in the beginning of the 9th Century. With the aid of mercenaries from Scandinavia (Varangians) who, since the middle of the 9th Century, had been serving in the armies of the princes of Kiev, the Kingdom during the 10th Century gave remarkable evidences of a very unusual activity of expansion. The Northern Slavic tribes, the forbears of the Russians of today, were subjugated, the nomadic tribes of the steppes were driven back, commercial and cultural relations were established with the Byzantine Empire. In the year 988 the Great Prince of Kiev (Vladimir the Great), together with all his peoples accepted Greek Christianity—with Slavic rites. There ensued, especially under his successor, Yaroslav the wise, a great advance in the material and spiritual civilization of the ancient Ukrainians. The fact that the ancient state of Kiev, as well as its civilization, was produced by the ancient Ukrainians, is evident, not only from the fact that the most ancient literary monuments of Kiev already show specifically Ukrainian peculiarities of language. A still more important piece of evidence is the constitution of the Kingdom of Kiev, which originated thru the amalgamation of the newly organized royal power with the original republican constitution of the Ukrainians. The ancient clan constitution has been of as fundamental importance for the historico-political tradition of the Ukraine as the Kingdom of Kiev itself. All the power of government rested originally in the hands of the general assembly of all freemen, whose decrees were executed by elected officials, consisting in part of the war-chieftains (probably the later princes). In the ancient [179]Kingdom of Kiev there was constant opposition between the power of the princes, which originated later and rested on military might, and the power of the clan assembly, sanctioned by long tradition. The Prince, his retainers, and the Boyar nobility, which gradually developed out of the body of retainers, were never liked by the people. The Kingdom of Kiev grew out of the union of trade, and was a union which at that time was necessary. The governmental system established by the princes of the Kiev dynasty, on foreign models, was inherently alien to the original social-political system of the Ukrainian People, so that the amalgamation of these two elements was difficult, in fact, almost impossible.