Great Moravia
Great Moravia (Czech: Velká Morava, Slovak: Veľká Morava), also Moravia or Great Moravian Empire, was the first West Slavic state to emerge from ""the most powerful tribal area in Central Europe"". Its core territories were located on the northern Morava River along the present-day border of the Czech Republic and Slovakia. Although, its extent and location have been called into question. The rival theories place its centre at the south of the river Danube or the Great Hungarian Plain. The exact date of the founding of the Moravian state is controversial, but it is supposed that the state building process was completed in the early 830s under Mojmir I (r. 820s/830s–846), who is the first known Moravian ruler.Mojmir and his successor, Rastislav (r. 846–870), initially acknowledged the suzerainty of the Carolingian monarchs, but their fights for independence caused a series of armed conflicts with East Francia beginning in the 840s. Moravia reached its largest territorial extent under Svatopluk I (r. 870–894), who was occasionally styled as king in contemporaneous sources. Although the borders of his empire cannot be exactly determined, he controlled the core territories of Moravia as well as other neighboring regions, including Bohemia and parts of present-day Slovakia, Hungary, Poland and Ukraine, for some period of his reign. Separatism and internal conflicts emerging after Svatopluk's death contributed to the fall of Moravia, which was overrun by the Hungarians. The exact date of Moravia's collapse is unknown, but it occurred in the period between 902 and 907.Moravia experienced significant cultural development after the arrival in 863 of the mission of Saints Cyril and Methodius, initiated by Prince Rastislav, which introduced a system of writing (the Glagolitic alphabet) and Slavonic liturgy, the latter eventually formally approved by Pope Adrian II. The Glagolitic script and its successor Cyrillic were disseminated to other Slavic countries (particularly Balkan states and Kievan Rus'), charting a new path in their cultural development.