From the Wikipedia page 
The Khrushchev Thaw (or Khrushchev's Thaw; Russian: Хрущёвская о́ттепель, tr. Khrushchovskaya Ottepel; IPA: [xrʊˈɕːɵfskəjə ˈotʲɪpʲɪlʲ] or simply Ottepel) refers to the period from the early 1950s to the early 1960s when repression and censorship in the Soviet Union were relaxed, and millions of Soviet political prisoners were released from Gulag labor camps due to Nikita Khrushchev's policies of de-Stalinization and peaceful coexistence with other nations.
The Thaw became possible after the death of Joseph Stalin in March 1953. Khrushchev denounced Stalin in The "Secret Speech" at the 20th Congress of the Communist Party, ] then ousted the pro-Stalinists during his power struggle in the Kremlin. The term was coined after Ilya Ehrenburg's 1954 novel The Thaw ("Оттепель"), sensational for its time. The Khrushchev Thaw was highlighted by Khrushchev's 1954 visit to Beijing, People's Republic of China, his 1955 visit to Belgrade, Yugoslavia (with whom relations had soured since the Tito–Stalin Split in 1948), and his subsequent meeting with Dwight Eisenhower later that year, culminating in Khrushchev's 1959 visit to the United States.
Inter alia led to demonstrations Georgia and the Polish and Hungarian Revolutions of 1956