Prince of Polotsk

The Princes of Polotsk ruled the Principality of Polotsk within the realm of Kievan Rus or within the Grand Duchy of Lithuania from the mid ninth century to 1307.

Rogvold, a non-Rurikid Varangian, was the first Prince of Polotsk. When Vladimir the Great returned from exile in Scandinavia in 980 to try to claim the Kievan throne that his brother, Yaropolk, held, he sought an alliance with Rogvolod through a marriage with his daughter, Rogneda. When she refused, calling Vladimir the "son of a slave," he attacked Polotsk, killed Rogvold and his son, and took Rogneda by force to be his wife. Polotsk was then granted to Vladimir's son, Izyaslav, around the time of Christianization (988), and when Izyaslav predeceased his father in 1001, the throne of Polotsk was passed on to Izyaslav's son, Briacheslav, and the Polotsk line (the senior branch of Vladimir's sons) became izgoi and was not legally allowed to succeed to the Kievan throne, although Bryacheslav's son, Vseslav, held briefly the Kievan throne in 1068-1069, after it was granted to him by the veche following the Kiev Uprising.

...
Wikipedia