Yermak Timofeyevich, a Cossack led the first campaign of Russian conquest of Siberia in the reign of Ivan the Terrible 1580-82 C.E. However, Kuchum Khan returned briefly and attacked Yermak on August 6, 1584 in the dead of night and killed most of his army. Finally, in August 1598 Küçhüm Khan was defeated at the Battle of Urmin near the River Ob. In the course of the fight the Siberian royal family were captured by the Russians. However, Küçhüm Khan escaped yet again. The Russians took the family members of Küçhüm Khan to Moscow and there they remained as hostages. The descendants of the khan's family became known as the Princes Sibirsky and the family is known to have survived until at least the late 19th Century. The struggle for dominance in the region continued for several years by the Taibughid successor Syed Ahmed Khan and the Shaybanid successor Ali ibn Kuchum Khan as well as the Russians.