The Russian Tsar IVAN was the first ruler of the Tsardom of Russia, reigning from 1547 to 1584. He was the grandson of IVAN III and the son of Vasili III. He is known for his expansion of the Tsardom of Russia, which included the conquest of the Khanates of Kazan, Astrakhan, and Siberia. He also established the Russian Orthodox Church as the official religion of the country. IVAN is remembered as one of the most influential rulers in Russian history.