As you alluded to, the Vikings that settled in Francia quickly assimilated with the Gallic Romans and the Germanic Franks to form a distinct Norman identity, which interestingly left a massive cultural legacy in Sicily and the Crusader states (though at this point were far from their Norse roots). There were also Scandinavians that settled along the Volga River as merchants, trading with both the Byzantines and the Muslims across the Black Sea and Caucasus. These people, known as the Varangians, ultimately formed the loosely organized Kievan Rus and assimilated with the Eastern Slavs and Fins already there, creating the cultural foundation of both the Russian and Ukrainian identity today.