Great Moravia (Latin: Regnum Marahensium; Greek: Μεγάλη Μοραβία, Meghálī Moravía; Czech: Velká Morava [ˈvɛlkaː ˈmorava]; Slovak: Veľká Morava [ˈvɛʎkaː ˈmɔrava]; Polish: Wielkie Morawy, German: Großmähren), or simply Moravia, was the first major state that was predominantly West Slavic to emerge in the area of Central Europe, possibly including territories which are today part of the Czech Republic, Slovakia, Hungary, Austria, Germany, Poland, Romania, Croatia, Serbia, Ukraine and Slovenia. The formations preceding it in these territories were Samo's tribal union (631–658) and the Pannonian Avar state (567–822).
Centered on the Morava River – which gave the realm its name – the core encompassed today’s Moravia in the eastern Czech Republic and adjacent western Slovakia. The kingdom saw the rise of the first-ever Slavic literary culture in the Old Church Slavonic language as well as the expansion of Christianity, first via missionaries from East Francia, and later after the arrival of Saints Cyril and Methodius in 863 and the creation of the Glagolitic alphabet, the first alphabet dedicated to a Slavic language. Glagolitic was subsequently replaced by the Cyrillic alphabet created in the First Bulgarian Empire.