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
In the 15th century, the grand princes of Moscow continued to consolidate Russian land to increase their population and wealth. The most successful practitioner of this process was Ivan III, who laid the foundations for a Russian national state. Ivan competed with his powerful northwestern rival, the Grand Duchy of Lithuania, for control over some of the semi-independent Upper Principalities in the upper Dnieper and Oka River basins.