Kievan Rus', from 882 CE to 1240 CE, was a federation of Slavic and Norse tribes. It is most known for adopting Orthodox Christianity in 988 CE, influencing their culture and mythology. They formed close cultural ties with Byzantium, which shaped their art, society, and religious beliefs.Their mythology involved mythical beings like the Domovoi, house spirits that protected homes, and Zmey Gorynych, a fearsome three-headed dragon symbolizing chaos and destruction.