A unitary Marxist–Leninist one-party state proclaimed 20 August 1949 under a Soviet-style constitution, aligned with the USSR as part of the Eastern Bloc. Governed first by the Hungarian Working People's Party, then (after the crushed 1956 Revolution) by the Hungarian Socialist Workers' Party under János Kádár, whose relatively liberalized 'Goulash Communism' earned Hungary a reputation as 'the merriest barrack in the socialist camp.'
Peaceful negotiated transition: Parliament adopted nearly 100 constitutional amendments in October 1989 converting the one-party Marxist–Leninist state into a multiparty democracy. The Republic of Hungary was officially proclaimed on 23 October 1989, replacing the People's Republic without violent rupture.
Narrative history of the 1956 uprising and Soviet crackdown that set the course of the Kadar-era People's Republic.