Answer
The fall of the Tatar Khanate of Kazan can be attributed to Ivan the Terrible's military campaign in 1552. This marked the end of Kazan's sovereignty and its incorporation into the Tsardom of Russia. Ivan's victory was facilitated by his superior military tactics, including the use of heavy artillery, and the disunity among Kazan's allies, ultimately leading to the demise of the powerful Tatar state.