Kievan Rus (kē´ĕfən), medieval state of the Eastern Slavs. It was the earliest predecessor of modern Ukraine and Russia. Flourishing from the 10th to the 13th cent., it included nearly all of present-day Ukraine and Belarus and part of NW European Russia, extending as far N as Novgorod and Vladimir. According to the Russian Primary Chronicle, a medieval history, the Varangian Rurik established himself at Novgorod c.862 and founded a dynasty. His successor, Oleg or Oleh (d. c.912), shifted his attention to the south, seized Kiev (c.879), and established the new Kievan state. The Varangians were also known as Rus or Rhos; it is possible that this name was early extended to the Slavs of the Kievan state, which became known as Kievan Rus. Other theories trace the name Rus to a Slavic origin. Oleg united the Eastern Slavs and freed them from the suzerainty of the Khazars. His successors were Igor or Ihor (reigned 912–45) and Igor's widow, St. Olga or Olha, who was regent until about 962. Under Olga's son, Sviatoslav or Svyatoslav (d. 972), the Khazars were crushed, and Kievan power was extended to the lower Volga and N Caucasus. Christianity was introduced by Vladimir I or Volodymyr I (reigned 980–1015), who adopted (c.989) Greek Orthodoxy from the Byzantines. The reign (1019–54) of Vladimir's son, Yaroslav the Wise, represented the political and cultural apex of Kievan Rus. After his death the state was divided into principalities ruled by his sons; this soon led to civil strife. A last effort for unity was made by Vladimir II or Volodymyr II (reigned 1113–25), but the perpetual princely strife and the devastating raids of the nomadic Cumans soon ended the supremacy of Kiev. In the middle of the 12th cent. a number of local centers of power developed: Halych in the west, Novgorod in the north, Vladimir-Suzdal (see Vladimir) in the northwest, and Kiev in the south. In 1169, Kiev was sacked and pillaged by the armies of Andrei Bogolubsky of Suzdal, and the final blow to the Kievan state came with the Mongol invasion (1237–40). The economy of the Kievan state was based on agriculture and on extensive trade with Byzantium, Asia, and Scandinavia. Culture, as well as religion, was drawn from Byzantium; Church Slavonic was the literary and liturgical language of the state. According to some scholars the history of the Kievan state is the common heritage of modern Russians, Ukrainians, and Belarusians, although their existence as separate peoples has been traced as far back as the 12th cent. Ukrainian scholars consider Kievan Rus to be central to the history of the Ukraine.
See G. Vernadsky, Kievan Russia (2d ed. 1973); J. L. Evans, The Kievan Russian Principality (1981).