Boris Rogvolodovich - Prince Drutsky in the 1180s - not earlier than 1196 , from the clan of the Polotsk princes , son of Prince Rogovolod Borisovich .
It is mentioned in the annals of 1196 when, in alliance with the Chernigovites and together with Prince Vasilk Volodarevich, he participated in a campaign against Vitebsk , which at that time was dependent on Smolensk . Boris distinguished himself in a battle that ended in the defeat of the Smolensk army. Having hit the Smolyan in the rear, he captured Prince Mstislav Romanovich , who commanded them, and transferred it to Prince Chernigov at his request. According to N. Ermalovich , the fact that Boris acted in alliance with the inhabitants of Polotsk indicates the return of Drutsk in 1180 under the influence of Polotsk .
N. Ermolovich “Ancient Belarus: Polotsk and Novogorodsky periods” (1990) (2nd edition)