There were two major periods during Russia's history when large territories formerly under its rule split away. The first was 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 independent states of Poland, Finland and the three Baltic states, while number of other territories obtained limited degree of sovereignty as the union republics (Treaty on the Creation of the Union of Soviet Socialist Republics). The second was the dissolution of the Soviet Union in 1990–1991 which led to the independence of its constituent union republics: Moldova, Belarus, Ukraine, Georgia, Armenia, Azerbaijan, Kazakhstan, Kyrgyzstan, Uzbekistan, Turkmenistan, Tajikistan, and the Baltic states of Lithuania, Latvia, and Estonia. Some of the aforementioned later became members of the European Union and NATO.