The Russian Empire, also known as Imperial Russia, was the final period of the Russian monarchy from its proclamation in November 1721, until its dissolution in late 1917. It consisted of most of northern Eurasia. The Empire succeeded the Tsardom of Russia following the Treaty of Nystad. The rise of the Russian Empire coincided with the decline of neighbouring rival powers: the Swedish Empire, the Polish–Lithuanian Commonwealth, Qajar Iran, the Ottoman Empire, and Qing China. It also held colonies in Russian America between 1799 and 1867. Covering an area of approximately , it remains the third-largest empire in history, surpassed only by the British Empire and the Mongol Empire; it ruled over a population of 125.6 million people per the 1897 Russian census, the only census carried out during the entire imperial period. It featured great ethnic, linguistic, religious, and economic diversity.
From the 10th to the 17th century, the land was ruled by a noble class known as the boyars, above whom was a tsar (later adapted as the "Emperor of all the Russias"). The groundwork leading up to the establishment of the Russian Empire was laid by Ivan III (1462–1505): he tripled the territory of the Russian state and laid its foundation, renovating the Moscow Kremlin and also ending the dominance of the Golden Horde.
Peter I (1682–1725) fought numerous wars and expanded an already vast empire into a major power of Europe. During his rule, he moved the Russian capital from Moscow to the new model city of Saint Petersburg, which was largely built according to designs of the Western world; he also led a cultural revolution that replaced some of the traditionalist and medieval socio-political customs with a modern, scientific, rationalist, and Western-oriented system. Catherine the Great (1762–1796) presided over a golden age: she expanded the Russian state by conquest, colonization, and diplomacy, while continuing Peter I's policy of modernization towards a Western model.