 In 882, his successor Oleg ventured south and conquered Kiev, which had been previously paying tribute to the Khazars.Oleg, Rurik's son Igor and Igor's son Sviatoslav subsequently subdued all local East Slavic tribes to Kievan rule, destroyed the Khazar khaganate and launched several military expeditions to Byzantium and Persia.In the 10th to 11th centuries Kievan Rus' became one of the largest and most prosperous states in Europe.