During his long reign, Ivan the Terrible nearly doubled the already large Russian territory by annexing the three Tatar khanates (parts of the disintegrated Golden Horde): Kazan and Astrakhan along the Volga, and the Siberian Khanate in southwestern Siberia. Thus, by the end of the 16th century, Russia expanded east of the Ural Mountains, thus east of Europe, and into Asia, being transformed into a transcontinental state.