Vikings took slavs as slaves. In Swedish "slav" means "slave". Vikings was rowers from Roslagen. In Finland they use the name Ruotsi for Sweden and Venäjä for Russia.
Ivar the Boneless, Varangians. When I was growing up in Ukraine, this was never ever mentioned in any literature, school, college. That the names like Oleg or Igor were not native threw a twist too, but they are very common names over there in UA/RU, on par with Ivan and Dmitry.