Old Czech in the context of "Hussites"

The Duchy of Bohemia, also later referred to in English as the Czech Duchy, (Old Czech: Češské kniežěstvie) was a monarchy and a principality of the Holy Roman Empire in Central Europe during the Early and High Middle Ages. It was formed around 870 by Czechs as part of the Great Moravian realm. Bohemia separated from disintegrating Great Moravia after Duke Spytihněv swore fealty to the East Frankish king Arnulf in 895.

While the Bohemian dukes of the Přemyslid dynasty, at first ruling at Prague Castle and Levý Hradec, brought further estates under their control, the Christianization initiated by Saints Cyril and Methodius was continued by the Frankish bishops of Regensburg and Passau. In 973, the Diocese of Prague was founded through the joint efforts of Duke Boleslaus II and Emperor Otto I. Later Duke Wenceslaus I of Bohemia, killed by his younger brother Boleslaus in September 935, became the land's patron saint.

The Hussites (Czech: Husité or Kališníci, "Chalice People"; Latin: Hussitae) were a Czech proto-Protestant Christian movement influenced by both the Byzantine Rite and John Wycliffe that followed the teachings of reformer Jan Hus (fl. 1401–1415), a part of the Bohemian Reformation.

The Czech lands had originally been Christianized by Byzantine Greek missionaries Saints Cyril and Methodius, who introduced the Byzantine Rite in the Old Church Slavonic liturgical language and the Byzantine tradition of Communion in both kinds administered by the holy spoon. Over the centuries that followed, however, the Roman Rite in Ecclesiastical Latin, which is less easily understood than Slavonic by native speakers of Old Czech, was imposed upon the Czech people despite considerable public resistance, by German-speaking bishops, beginning with Wiching, from the Holy Roman Empire. (See also Sázava Monastery). As a cultural memory of both communion in both kinds and the Divine Liturgy in a language closer to the vernacular is believed to have survived well into the Renaissance, the ideas of Jan Hus and others like him swiftly gained a wide public following. After the trial and execution of Hus at the Council of Constance, a series of crusades, civil wars, victories and compromises between various factions with different theological agendas broke out. At the end of the Hussite Wars (1420–1434), the now Catholic-supported Utraquist side came out victorious from protracted conflict against Jan Žižka and the Taborites, who embraced the more radical theological teachings of John Wycliffe and the Lollards, and became the dominant Hussite group in Bohemia.