Prince of Smolensk

The Prince of Smolensk was the kniaz, the ruler or sub-ruler, of the Rus' Principality of Smolensk, a lordship based on the city of Smolensk. It passed between different groups of descendants of Grand Prince Iaroslav I of Kiev until 1125, when following the death of Vladimir Monomakh the latter's grandson Rostislav Mstislavich was installed in the principality, while the latter's father Mstislav I Vladimirovich became Grand Prince. It gained its own bishopric in 1136. It was Rostislav's descendents, the Rostaslavichi, who ruled the principality until the fifteenth-century. Smolensk enjoyed stronger western ties than most Rus' principalities.

...
Wikipedia