Russian Empire
Though the Empire was only officially proclaimed by Tsar Peter I following the Treaty of Nystad (1721), some historians would argue that it was truly born either when Ivan III of Russia conquered Veliky Novgorod in 1478, or when Ivan the Terrible conquered the Khanate of Kazan in 1552. According to another point of view, the term "Tsardom", which was used after the coronation of Ivan IV in 1547, was already a contemporary Russian word for empire.
History of Russia (1855–92)
Russia continued to expand its empire, occupying the Caucasus, Tashkent and Samarkand. In foreign affairs, the period began with the conclusion of the Crimean War. Russian policy brought it into conflict with other European powers, in particular Austria-Hungary, as it sought to extend influence over the European portions of the receding Ottoman Empire and regain naval access to the Black Sea. This culminated in a successful war with the Ottoman Empire in 1877–1878, followed by the Treaty of San Stefano and Congress of Berlin in 1878 by which an independent Bulgaria came into being, and by acquisition of former Ottoman territories in the South Caucasus. Russia joined Germany and Austria-Hungary in the League of the Three Emperors, but friction continued with both partners over Bulgaria, and the alliance with Germany came to an end in 1890.