The "Era of Stagnation" (Períod zastóya, or Эпо́ха засто́я ) is a term coined by Mikhail Gorbachev in order to describe the negative way in which he viewed the economic, political, and social policies of the Soviet Union that began during the rule of Leonid Brezhnev (1964–1982) and continued under Yuri Andropov (1982–1984) and Konstantin Chernenko (1984–1985). It is sometimes called the "Brezhnevian Stagnation" in English. During the period of Brezhnev's leadership, the term "Era of Stagnation" was not used. Instead Brezhnev used the term "period of developed socialism" (Russian: период развито́го социализма) for the period that started in 1971. This term stemmed from Khrushchev's promise in 1961 of reaching communism in 20 years. It was in the 1980s that the Soviet leader Mikhail Gorbachev coined the term "Era of Stagnation" to describe the economic difficulties that developed when Leonid Brezhnev led the Soviet Union from 1964 to 1982. Scholars have subsequently disagreed on the dates, significance and causes of the stagnation. Supporters of Gorbachev have criticised Brezhnev, and the Brezhnev administration in general, for being too conservative and failing to change with the times. After the death of Soviet leader Joseph Stalin in 1953, a program of policy change was begun, later known as de-Stalinization. Nikita Khrushchev, who succeeded Stalin's brief successor Georgy Malenkov as Soviet leader, introduced relatively liberal reforms during the period known as the Khrushchev Thaw. This period also brought an economic increase that topped at 6%. However the Manege Affair of 1962, during which Khrushchev publicly criticised an exhibition of Soviet art, led to the reassertion of Communist Party control over the arts and marked the beginning of the end of the Cultural Thaw. Brezhnev replaced Khrushchev as Soviet leader in 1964. The Brezhnev Era (1964–1982) began with high economic growth and soaring prosperity, but gradually significant problems in social, political, and economic areas accumulated.