Great Moravia (Latin: Regnum Marahensium; Greek: Μεγάλη Μοραβία, Megale Moravia; Czech: Velká Morava; Slovak: Veľká Morava; Polish: Wielka Morawa), the Great Moravian Empire, or simply Moravia, was the first major state that was predominantly West Slavic to emerge in the area of Central Europe, chiefly on what is now the territory of the Czech Republic, Slovakia, Poland (including Silesia), and Hungary. The only formation preceding it in these territories was Samo's Empire known from between 631 and 658 AD. Great Moravia was thus the first joint state of the Slavonic tribes that became later known as Czechs and Slovaks and that later formed Czechoslovakia.
Its core territory is the region now called Moravia in the eastern part of the Czech Republic alongside the Morava River, which gave its name to the kingdom. 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 after the arrival of St. Cyril and St. Methodius in 863 and the creation of the Glagolitic alphabet, the first alphabet dedicated to a Slavonic language, which had significant impact on most Slavic languages and stood at the beginning of the modern Cyrillic alphabet.
Moravia reached its largest territorial extent under the king Svätopluk I, (Svatopluk in Czech), who ruled from 870 to 894. Although the borders of his empire cannot be exactly determined, he controlled the core territories of Moravia as well as other neighbouring regions, including Bohemia, most of Slovakia and parts of Slovenia, Hungary, Poland and Ukraine, for some periods of his reign. Separatism and internal conflicts emerging after Svätopluk's death contributed to the fall of Great Moravia, which was overrun by the Hungarians who then included the territory of the now Slovakia in their domains. The exact date of Moravia's collapse is unknown, but it occurred between 902 and 907.
Moravia experienced significant cultural development under King Rastislav, with the arrival in 863 of the mission of Saints Cyril and Methodius. After his request for missionaries had been refused in Rome, Rastislav asked the Byzantine emperor to send a "teacher" (učitelja) to introduce literacy and a legal system (pravьda) to Great Moravia. The request was granted. The missionary brothers Cyril and Methodius introduced a system of writing (the Glagolitic alphabet) and Slavonic liturgy, the latter eventually formally approved by Pope Adrian II. The Glagolitic script was probably invented by Cyril himself and the language he used for his translations of holy scripts and his original literary creation was based on the Slavic dialect he and his brother Methodius knew from their native Thessaloniki. The language, termed Old Church Slavonic, was the direct ancestral language for Bulgarian, and therefore also referred to as Old Bulgarian. Old Church Slavonic, therefore, differed somewhat from the local Slavic dialect of Great Moravia which was the ancestral idiom to the later dialects spoken in Moravia and western Slovakia.
Later, the disciples of Cyril and Methodius were expelled from Great Moravia by King Svätopluk I, who re-orientated the Empire to Western Christianity. Nevertheless, the expulsion had a significant impact on countries where the disciples settled and from there continued their evangelizing missions - especially Southeastern Europe and later Eastern Europe. Arriving in the First Bulgarian Empire, the disciples continued the Cyrilo-Methodian mission and the Glagolitic script was substituted by Cyrillic which used some of its letters. The Cyrillic script and translations of the liturgy were disseminated to other Slavic countries, particularly in the Balkans and Kievan Rus', charting a new path in these Slavic nations' cultural development and establishing the Cyrillic alphabets as they are now known in Bulgaria, Belarus, Macedonia, Mongolia, Montenegro, Russia, Serbia, and Ukraine.
The meaning of the name of Great Moravia has been subject to debate. The designation "Great Moravia" - Megale Moravia (Μεγάλη Μοραβία) in Greek - stems from the work De Administrando Imperio written by the Byzantine Emperor Constantine VII Porphyrogenitos around 950. The emperor only used the adjective megale in connection with the polity when referring to events that occurred after its fall, implying that it should rather be translated as "old" instead of "great". According to a third theory, the megale adjective refers to a territory located beyond the borders of the Byzantine Empire. Finally, the historian Lubomír E. Havlík writes that Byzantine scholars used this adjective when referring to homelands of nomadic peoples, as demonstrated by the term "Great Bulgaria".
The work of Porphyrogenitos is the only nearly contemporaneous source using the adjective "great" in connection with Moravia. Other documents from the 9th and 10th centuries never used the term in this context. Instead they mention the polity as "Moravian realm" or "realm of Moravians" (regnum Marahensium, terra Marahensium, regnum Marahavorum, regnum Marauorum, terra Marauorum or regnum Margorum in Latin, and Moravьska oblastь in Old Church Slavonic), simply "Moravia" (Marawa, Marauia, and Maraha in Latin, Morava, Marava, or Murava in Old Church Slavonic, and M.ŕawa.t in Arabic), also regnum Sclavorum (realm of Slavs) or alternate regnum Rastizi (realm of Rastislav) or regnum Zuentibaldi (realm of Svätopluk).