During the Viking Age, the Semigallians were involved in battles with Swedish Vikings over control of the lower part of the Daugava waterway. In "Gesta Danorum" the Danish chronicler Saxo Grammaticus wrote that the Viking Starkad crushed the Curonians, all the tribes of Estonia, and the peoples of Semgala. When the Rurikid successors of the Varangians tried to subjugate the Semigallians, they defeated the invading army of Polotsk led by Prince Rogvolod Vseslavich in 1106. Ancient chronicles claim that 9000 of their soldiers were killed.