Both the origin of the Kievan state and that of the name Rus, which came to be applied to it, remain matters of debate among historians. According to the traditional account presented in The Russian Primary Chronicle, it was founded by the Viking Oleg, ruler of Novgorod from about 879. In 882 he seized Smolensk and Kiev, and the latter city, owing to its strategic location on the Dnieper River, became the capital of Kievan Rus. Extending his rule, Oleg united local Slavic and Finnish tribes, defeated the Khazars, and, in 911, arranged trade agreements with Constantinople.

https://www.britannica.com/topic/Kyivan-Rus

Who wants to bet 420 was another marker event?

Talk about holding a grudge…