Ukraine was not widely called by its present name until the 19th century. Different parts of Ukraine were invaded and occupied in the first millennium BC by the Cimmerians, Scythians, and Sarmatians and in the first millennium of the Christian by the Goths, Huns, Bulgars, Avars, Khazars, Magyars, and Pechenegs.
The most significant development of this entire period, however, was the movement of some Slavic tribes in the 5th and 6th centuries from their primordial homeland north of Carpathian Mountains eastward into forest and forest-steppe region of western and north-central Ukraine. From there the Slavs would eventually expand farther north into territories of the future Russian state around Moscow.
Among Slavs’ earliest settlements was that of Kiev along Dnepr River, which was the capital of Polianian tribe among them. The state known as Kievan Rus arose from the intermixture of Polianians with those Varangians (Norsemen) who controlled Dnepr River trade route connecting Baltic Sea with Byzantium.
The name Rus, which first designated the lands around Kiev, later came to include the entire Kievan domain.
Kievan Rus state reached its zenith in the 10th and 11th centuries under the rulers Vladimir I (St. Vladimir) and his son Yaroslav I (Yaroslav the Wise). Vladimir I adopted Christianity as the official religion of his realm about AD 990, and church hierarchy was formed under the auspices of Byzantines and patriarch at Constantinople.
Christianity gave eastern Slavic people their first written language, called Church Slavonic. Kiev Rus reached the height of its power in the 11th century, and Kiev became eastern Europe’s chief political and cultural center.
Kievan Rus map