Fall of the Soviet Union.
Date: 1991
In 1991, the Soviet Union breaks up into 15 states, including Russia. Some republics had already left the Soviet Union due to internal political crises and economic turmoil.
Soviet Union leader Mikhail Gorbachev resigns from office, and the Belovezha Accords are signed on December 8, 1991: "by President Boris Yeltsin of Russia, President Kravchuk of Ukraine, and Chairman Shushkevich of Belarus, recognizing each other's independence and creating the Commonwealth of Independent States (CIS) to replace the Soviet Union" (Wikipedia contributors, n.d.).