From the 9th century, the history of Slovakia has been materialised in written sources. Old Slavonic names of settlements and names of important people captured in the writings are the oldest evidence of the development of the national identity of Slovaks. The town of Nitra and its ruler, Prince Pribina, became the centre of the principality. Prince Pribina built in the year 828 the oldest Christian church in the territory of western and eastern Slavs. Following the overthrow of the Avars by Charlemagne in the late 8th century, the Slavic communities living either side of the White Carpathian mountain range evolved into the principalities of Moravia and Nitra. In 833 Mojmir of Moravia attacked Nitra, driving its ruler Pribina out of the region, and thus uniting the two Slavic principalities into what was later referred to by Byzantine Emperor Constantine VII as the Great Moravian Empire.
The most significant event which definitely affected the further development of Slovakia was the arrival of two Byzantine brothers, Constantine (Cyril) and Methodius, in 863. These two Christian scholars and philosophers created the first Slavonic alphabet, called Glagolitic, and wrote several books in it, including a Bible. By officially adopting Christianity, Slovakia integrated itself into Christian Europe, gaining some extraordinary privileges, including that of making a liturgy in its own language. Thanks to such a privilege, the Old Church Slavonic language was at the same level with Latin and Greek, overrunning such languages as French and English.
Great Moravia fell apart after attacks by Bavarians and Ugrians, and after 906 there are no further reports about it. Apart from written artefacts, Great Moravian monuments are mostly the concern of archaeology. Excavations of Old Slavonic settlements and burial grounds have revealed abundant artefacts, including ceramics, jewellery, weapons and other objects. The new religion revealed itself in the accoutrements found in graves, as well as in Great Moravian stone architecture which is represented by churches of three types – the one-nave church, the three-nave basilica and the rotunda. These architectural styles were mainly influenced by the Bavarian and Dalmatian-Istrian, respectively Byzantine styles. The most significant Great Moravian sacral monuments in the form of rotundas and basilicas are situated in the locality of Nitra, Bratislava, Devín, Moravany nad Váhom, Bíňa and Kopčany. The Church of St. Margaret of Antioch, situated in the small village of Kopčany, close to the Moravian village of Mikulčice, was built in the mid 9th century and has almost authentically been kept until today. The beginning of church administration dates back to the 9th century when the first Benedictine monastery was built on Zobor hill. Slovak history has not yet given up all of its secrets. Only the very latest research brings evidence that the foundations of many still functioning churches were built in the 9th, 10th and 11th centuries, when they represented a key factor in the Pagan world transforming into the Christian world. At the same time, they indicate the persistent development of Old Slavonic settlements which came to form part of the newly-established Kingdom of Hungary. Pagan elements may still be found in many demonstrations of folk culture, forming part of Slovak folklore even to the present day. However, the route of official art, whether in architecture or works of creative art, pursued the Christian ethic, supported by the clerical and secular establishment.