I've read several people talking about Ukraine (from where I originate), but honestly that would be a bad choice - we have never been important in world arena.
Now, Kievan Rus' would be a much better choice to represent the importance and power of Kiev that it held for couple of centuries during medieval times. To avoid the same city names with Russian civ it could be given all city names that were situated in Ukrainian and Belarus territories that Russian empire civ does not have for some reason - Kiev as capital, then Chernigov, Vyshgorod, Turov, Kremenets, Vladimiri-Volynskiy, Galich etc.
Vladimir the Great would be civ's leader and the unique ability would be "From the Varangians to the Greeks" - every worked tile near the river produces additional 1 gold.
UU would be "Druzhina" that would replace Knight unit. In addition to standart Knight feats, it would produce income of +1 Gold if garissoned in your city (+2 Gold if garissoned in a puppet).
UB would be "Church" that would replace Temple. Contrary to Temple, Church would not have any maintanance cost while providing the same Faith income.