The period of Russian expansionism begins with the accession of Ivan IV (Ivan the terrible) in 1533. Under his rule Russia expanded south eastwards down the River Volga to annexe the khanates of Kazan and Astrakhan which blocked the trade routes to the Middle East through the Caspian Sea. By the early 16th century the process of colonising Siberia was underway and Russia then turned its attention to the west and south west. It encroached into the eastern territories of Sweden, Finland, Lithuania, Estonia, Livonia, and the eastern Ukraine. It also gained control of the Khanate of Crimea in 1783. By the late 18th century Russia had become a massive Eurasian empire and still expanding into the territories of the Ottoman Empire to the south.