Answer
The Russian Cossack leader Yermak Timofeyevich launched his campaign against the Khanate of Sibir in 1582, marking a pivotal moment in Russian expansion into Siberia. Yermak's forces, consisting of Cossacks and allied Siberian tribes, capitalized on internal conflicts within the khanate and their superior military tactics to achieve a decisive victory over the Siberian Khan Kuchum.