Princely era (kniazha doba). The term used by non–Soviet Ukrainian historians, and some Russian historians, to designate a 500-year period in the Middle Ages when the East Slavic princes held political power over the territory of present-day Ukraine. The princely era encompasses (1) the period from the creation of the independent Kyivan Rus’ state in the 9th century to its disintegration after the Mongol-Tatar invasion of 1240, and (2) the contiguous period of the independent Principality of Galicia-Volhynia, which disintegrated after the death of its last prince, Yurii II Boleslav, in 1340.
Most modern non–Soviet Ukrainian historians have adhered to Mykhailo Hrushevsky's scheme of Eastern Slav history, in which the princely era is treated as an integral part of Ukrainian history. According to Hrushevsky ‘the Kyivan state, law, and culture were the creation of a single nationality—the Ukrainian-Rus’ [nationality]’ and ‘the Kyivan period merged with the Galician-Volhynian period in the 13th century.’ Most Russian and some Western historians have viewed the era as belonging solely to Russian history. The term ‘princely era’ was not used at all in Soviet historiography. Instead Soviet historians used the term ‘period of feudalism’ and propounded the officially sanctioned view that an ‘ancient Rus’ people’ and the ‘ancient Rus’ state’ were the cradle of three ‘fraternal’ peoples, the Russians, Ukrainians, and Belarusians. Ukrainian historians in the West (and most historians in independent Ukraine) have rejected the appropriation of the princely era by Russian historians and the Soviet fraternal peoples theory, viewing it as a veiled version of the Russian imperialist interpretation.
Encyclopedia of Ukraine