Ukraine hasn't had much independence in it's long history. For much of history it seems like it was controlled by the Russian Empire, the USSR, Austra-Hungary, the Golden Horde, Poland, Lithuania, and probably others. There was some brief independence after the fall of the Russian Empire. In 1919 it became the Ukraine Soviet Socialist Republic and joined the Soviet Union in 1922. (http://www.mapsofworld.com/pages/fast-facts/ukraine/) So I don't think that Kievan Rus is a good starting point for Ukraine as a nation, especially when so many other nations claim successorship from it.

Russia is just as confusing. I'd say a good starting point would be the defeat of the Khanate by Ivan the Terrible in the 1500s. This would lead to the Russian Empire which would lead to the Soviet Union which would lead to the Russian Federation that we see today. (http://www.historyhaven.com/APWH/unit%203/Russia_notes.htm)

So the Kievan Rus came before Russia, but I think Russia has existed in a relative continuum, meaning not controlled by foreign powers, for longer.