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.
Secession in Russia
In Russian history, there were two periods during which significant territories fell away from it. The first is the disintegration of the Russian Empire as a result of the February and October revolutions in 1917–1921. Active disintegration processes began in the economy, social structure, public and political spheres of the Russian Empire, which ultimately led to the end of the Tsarist regime and became parts of independent states as Poland, Finland and Romania. The second is the dissolution of the Soviet Union in 1990–1991 which to the independence of the 15 republics of the USSR (Lithuania, Latvia, Estonia, Belarus, Ukraine, Georgia, Armenia, Azerbaijan, Kazakhstan, Kyrgyzstan, Uzbekistan, Turkmenistan and Tajikistan).