A medieval East Slavic federation from the 9th–13th centuries ruled by the Rus’ and centered in Kyiv. Much like the
Eastern Roman Empire being referred to as "Byzantine Empire", the term “Kievan Rus” wasn’t used back then, it was invented later by
historians to
distinguish the Kyivan-centered period from later Russian states. In its own time, it was just called “the land of the Rus’.”