The Cumans, who had emerged as the dominant power of the Pontic steppes in the early 1060s, invaded the southern regions of Kievan Rus' in 1068. The three brothers together marched against the invaders, but the Cumans routed them on the Alta River. From the battlefield, Sviatoslav withdrew to Chernigov and regrouped his troops. He returned to defeat the Cumans with a smaller force at the town of Snovsk on 1 November, thus enhancing his prestige among the populace. In the meantime, the townspeople of Kiev had dethroned and expelled Sviatoslav's brother, Iziaslav. Taking advantage of Iziaslav's absence, Sviatoslav sent his own son, Gleb, to Novgorod to rule the town.