The all-scale, often economical, change that occured in the 80's in the Soviet Union. Ultimately, perestroika collapsed the age of the Soviets. Now, the Soviet Union is called the CIS (Commonwealth of Independant States), aka : Russia.
"We live in a sad age...imperialism...totalitarianism...perestroika..."
-Revolver Ocelot in MGS2, after Snake survives the second round of torture