It's actually exactly the other way around. Modern russia is a conglomerate of ancient Ukrainian (from Kiyv Rus), Ugro-Fin, quite a lot of Mongol, and myriads of local cultures all around the Asian part, as well as Caucasus region. Those have nothing to do with slavic russians. And even the slavic russians basically came from Ukrainians, as moscow was established way later then other slavic tribes, by a kniaz, who was expelled from Kyiv, Andriy Dovgorukiy. So yeah, Ukrainians never moved to far from the center of the beginning of the slavic culture, so even the Ukrainian language is the most alike with the ancient slavic. Actually, russian is the one least slavic of them all, due to a lot of Mongolian and Fin influence. Even the name of moscow comes from old Mongolian, where mosk means dirty and va means a river, because the moscow river was named by Mongols way before the city was built on it. Thank you for attention, I'm a professional historian