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
Daniil Aleksandrovich, the youngest son of Alexander Nevsky, founded the principality of Moscow (known as Muscovy in English), which first cooperated with and ultimately expelled the Tatars from Russia. Well-situated in the central river system of Russia and surrounded by protective forests and marshes, Moscow was at first only a vassal of Vladimir, but soon it absorbed its parent state.