Kievan Rus' was founded in the territory of the Eastern Polans, who lived among the rivers Ros, Rosava, and Dnieper. Russian historian Boris Rybakov came from studying the linguistics of Russian chronicles to the conclusion that the Polans union of clans of the mid-Dnieper region called itself by the name of one of its clans, "Ros", that joined the union and was known at least since the 6th century far beyond the Slavic world. The origin of the Kyiv princedom is of a big debate and there exist at least three versions depending on interpretations of the chronicles. In general it is believed that Kievan Rus' included the central, western and northern part of modern Ukraine, Belarus, the far eastern strip of Poland and the western part of present-day Russia. According to the ''Primary Chronicle'' the Rus' elite initially consisted of Varangians from Scandinavia.