 He died fighting against his unclesVsevolod Yaroslavich, Prince of Chernigov and Izyaslav Yaroslavich, Grand Prince of Kievon 3 October 1078.Boris was the son of Vyacheslav Yaroslavich, Prince of Smolensk, a younger son of Yaroslav the Wise, Grand Prince of Kiev.According to the historian Martin Dimnik, Boris was a child when his father died in 1057.