Moses the Hungarian

Moses the Hungarian (Russian: Моисей Угрин, Moisey Ugrin; Hungarian: Magyar Mózes) (died July 26, 1043) was a Kievan Russian monk of Hungarian origin. He is venerated as a saint by the Eastern Orthodox Church.

Moses was born around 990-995. He probably left Transylvania to serve the princely family in Kiev. Between 1015 and 1018, already preparing to become a monk, he was in the escort of Predslava, the daughter of Vladimir I of Kiev and sister of the future Prince Yaroslav I the Wise.

Following the Polish expedition of 1018, he was carried to Poland as a prisoner and could only return in 1025. Moses spent the rest of his life in the Kiev Cave Monastery.

Although the Hungarians were mostly pagan when he was born, and later they became an Orthodox Christian, the Hungarian chieftain of Transylvania, the Gyula, was baptized in Constantinople, which made it possible for Moses to travel to Kiev and settle there.

...
Wikipedia