Answer
The ambush of Yermak in 1584, carried out by Tatar forces, marked a significant event during Yermak's Siberian expedition. The surprise attack resulted in the death of Yermak and a major setback for the Russian forces seeking to expand their influence into Siberia. This incident highlights the challenges and risks encountered by Yermak and his men as they ventured into unfamiliar territories and faced resistance from local groups.