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
The History of Russia begins with that of the East Slavs and the Finno-Ugric peoples. The traditional beginning of Russian history is the establishment of Kievan Rus', the first united Eastern Slavic state, in 882. The state adopted Christianity from the Byzantine Empire in 988, beginning the synthesis of Byzantine and Slavic cultures that defined Orthodox Slavic culture for the next millennium. Kievan Rus' ultimately disintegrated as a state due to the Mongol invasions in 1237–1240 along with the resulting deaths of about half the population of Rus'.