What peoples of Central and Eastern Europe became part of the Roman Catholic Church?

Various peoples of Central and Eastern Europe, including the Poles, Hungarians, Czechs, Slovaks, and Croats, became part of the Roman Catholic Church through a combination of missionary efforts and political alliances. The Christianization of these regions was often facilitated by the influence of powerful rulers who adopted Catholicism, such as Mieszko I of Poland and Stephen I of Hungary, leading their subjects to follow suit. Additionally, the establishment of ecclesiastical structures and the cultural impact of the Catholic Church played significant roles in integrating these communities into the broader Catholic tradition.