Kyi 's legacy along with Shchek 's is mentioned in the Book of Veles , the authenticity of which , however , is disputed .
Some historians speculate that Kyi was a Slavic prince of eastern Polans in the 6th century .
prince 's legacy along with prince 's is mentioned in the Book of Veles , the authenticity of which , however , is disputed .
Some historians speculate that Kyi was a Slavic prince of eastern Polans in the 6th century .