Когда Киев вошел в состав Русского государства?
("Rosiya"), , other-Scand. "Garðar", "Garðaríki") is a medieval state in Eastern Europe, which arose in the 9th century as a result of the unification of East Slavic tribes under the rule of the princes of the Rurik dynasty. The term "Kievan Rus" is historiographical and was formed by historians to designate an era in the history of Rus when the center was in Kyiv. In the period of its highest prosperity, the Old Russian state occupied the territory from the Taman Peninsula in the south, the Dniester and the upper reaches of the Vistula in the west to the upper reaches of the Northern Dvina in the north. By the middle of the XII century, it entered a state of fragmentation and actually broke up into a dozen and a half separate Russian principalities, ruled by different branches of the Rurikovich. Until the Mongol invasion (1237-1240), Kyiv formally continued to be considered
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