Not entirely. To make it short and avoid digging into ancient history, before the rise of Germany there were two major powers in the region: Russia, and the Polish-Lithuanian Commonwealth. The latter was made up of largely Poles and Ruthenians. Its heartland consisted of roughly the modern-day Lithuania, Poland, and Western Ukraine. This polity expanded eastward while Russia was embroiled in a civil war, tacking on the now-occupied eastern areas of Ukraine, which are ethnically distinct - the people there are Russians, not Ruthenians. This was their high water line - once Prussia rose to power and Germany began to coalesce as a single political entity, the Polish-Lithuanian commonwealth fell apart and was absorbed by nearby regional powers, mostly Russia & Germany. In WWII the Ruthenians and Poles spent a lot of time slaughtering one another, and then ended up both falling behind the Iron Curtain. Now they are once again warmly reunited in their schizo slav crusade against all things Russians.
Crimea is a completely different story. It was one of the last strongholds of the remnants of the Mongol Golden Horde (these people ended up being called 'Tatars'). The Russian empire genocided/relocated most of them (as they were wont to do) and took the peninsula, repopulating it with mostly Russians. During the Soviet era, it was attached to Ukraine (at that time an internal territory) in order to streamline administration, and the Russians were very upset to lose it after the fall of the Soviet Union, when the Ukraine ('borderlands') were split into their own country - including Crimea. which is very important to Russia strategically and has zero historical/cultural ties to the Ruthenian heartland. Ultimately that's the root of the whole conflict - kind of funny in a cosmic sense that some bored Soviet clerk editing lines on a map would end up causing such a hubub. It's also why Russia had no problem taking or holding Crimea - it doesn't really have a strong national identity tying it to the rest of Ukraine.