There were two groups of “Kenaanim” in Europe: Czech Jews (speaking West Slavic) and Early Belarusian/Ukrainian Jews (speaking East Slavic). They are called West Knaan and East Knaan respectively by scholars like Alexander Beider. Both groups were primarily descended from Jews of western and southern Europe. East Slavic-speaking Jews had a small additional element from Romaniote Jews.
The Slavic-speaking Jews intermarried with Ashkenazic Jews and switched to Yiddish. The Ashkenazic people divided into subgroups such as Litvaks, Yekke, and Galitzianers.
It turns out that the Knaanim and the Ashkenazim never intermarried with the Khazars even though that had been speculated for a long time and I used to believe it was a possibility too. Genetic evidence disproved it starting in 2013.
Other Jewish ethnic groups that have lived in Russia at various times include the Karaite Jews, Krymchak Jews, and Mountain Jews. The Mountain Jews are not accurately classified as “Sephardim” but rather as “Mizrahim”. The real Sephardic culture developed in Spain and Portugal.
Krymchak Jews and Ashkenazi Jews intermarried to a limited extent with Sephardic Jews after 1492.
Details about all this are in my book “The Jews of Khazaria, Third Edition” (Rowman and Littlefield, 2018) in chapter 10.