the Italian peninsula as well as Malta and also existed in isolated pockets of papal jurisdiction in other parts of Europe, including Avignon. The Catholic Reformation began in 1545 when the Council of Trent was called in reaction to the Protestant Rebellion. The idea was to reform the state of worldliness and disarray that had befallen some of the clergy of the Church, while reaffirming the spiritual authority of the Catholic Church and its position as the sole true Church of Christ on Earth. The effort sought to prevent further damage to the Church and her faithful at the hands of the newly formed Protestant denominations. Tsardom of Russia In development of the Third Rome ideas, the Grand Duke Ivan IV (the "Awesome" or "the Terrible") was officially crowned the first Tsar ("Caesar") of Russia in 1547. The Tsar promulgated a new code of laws (Sudebnik of 1550), established the first Russian feudal representative body (Zemsky Sobor) and introduced local self-management into the rural regions. During his long reign, Ivan IV nearly doubled the already large Russian territory by annexing the three Tatar khanates (parts of disintegrated Golden Horde): Kazan and Astrakhan along the Volga River, and Sibirean Khanate in South Western Siberia. Thus by the end of the 16th century Russia was transformed into a multiethnic, multiconfessional and transcontinental state. Russia experienced territorial growth through the 17th century, which was the age of Cossacks. Cossacks were warriors organized into military communities, resembling pirates and pioneers of the New World. The native land of the Cossacks is defined by a line of Russian/Ruthenian town-fortresses located on the border with the steppe and stretching from the middle Volga to Ryazan and Tula, then breaking abruptly to the south and extending to the Dnieper via Pereyaslavl. This area was settled by a population of free people practicing various trades and crafts. In 1648, the peasants of Ukraine joined the Zaporozhian Cossacks in rebellion against Poland–Lithuania during the Khmelnytsky Uprising, because of the social and religious oppression they suffered under Polish rule. In 1654 the Ukrainian leader, Bohdan Khmelnytsky, offered to place Ukraine under the protection of the Russian Tsar, Aleksey I. Aleksey's acceptance of this offer led to another Russo-Polish War (1654–1667). Finally, Ukraine was split along the river Dnieper, leaving the western part (or Right-bank Ukraine) under Polish rule and eastern part (Left-bank Ukraine and Kiev) under Russian. Later, in 1670–71