In the 1970s, Wrocław and Łodź became the major centers of Polish experimental filmmaking. In Łodź, the progressive film movement originated from the city's film school (Państwowa Wyższa Szkoła Filmowa, Telewizyjna i Teatralna im. Leona Schillera w Łodzi), which had trained film and television professionals since its foundation in 1948. Although the school nurtured talented individuals such as Roman Polański and Andrzej Wajda from the very beginning, it was only in 1956, following the death of Poland's Stalinist hard-line leader Bolesław Bierut, that the period of political and cultural thaw supplanted the era of socialist realism in all arts, including film. The film school faced another challenge in 1968, following a campaign of anti-Semitic persecution across Poland that forced the rector of the school and numerous faculty members to step down, leading to a decline in the quality of the school's education. The goal of the school was always to provide classical film training for artists interested in making traditional—narrative—films for broad theatrical distribution. This applied both to the productions that followed socialist realist conventions and to the works of the Polish Film School, which attempted to break ties with this doctrine and to set film free, at least to a certain degree, from state supervision and censorship.