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.
Russian Empire
The Russian Empire, also known as Imperial Russia or simply Russia, was an empire that existed across Eurasia and North America from 1721, following the end of the Great Northern War, until the Republic was proclaimed by the Provisional Government that took power after the February Revolution of 1917.