The Slavic tribes settled in the territory of present-day Slovakia in the 5th century. Western Slovakia was the centre of Samo's empire in the 7th century. A Slavic state known as the Principality of Nitra arose in the 8th century and its ruler Pribina had the first known Christian church of the territory of present-day Slovakia consecrated by 828. Together with neighbouring Moravia, the principality formed the core of the Great Moravian Empire from 833. The high point of this Slavonic empire came with the arrival of Saints Cyril and Methodius in 863, during the reign of Duke Rastislav, and the territorial expansion under King Svätopluk I.