Son of the Polotsk Prince Iziaslav Volodymyrovych, from whom he inherited the Polotsk throne. In his young years the Polotsk Principality was governed probably by his mother and the boyar elite. Under his reign Polotsk was built up on a new site, and the Cathedral of Our Lady was constructed, in which the Prince’s brother was reburied in 1007. It looks as if the Polotsk Principality attempted to become independent of Kyiv during the struggle for the power of the Grand Prince.
In 1020 Prince Yaroslav the Wise won the victory over Briachyslav, and in 1021 the Polotsk Prince suffered the second defeat. Signing the peace treaty, Briachyslav recognized officially the supremacy of Kyiv and got into possession Vitebsk and Usviat. In 1026–1036, after Yaroslav’s defeat in his struggle with his brother Mstyslav, Briachyslav could act independently of Kyiv, but in 1036 he again recognized the supremacy of the Kyivan Prince.
Portrait (imaginary) of Briachyslav Iziaslavych