Moses was born around 990–995. Although the Hungarians were mostly pagan at the time (though they later became Christians), the Hungarian chieftain Gyula of Transylvania was baptized in Constantinople. This probably made it possible for Moses to leave Transylvania to serve the princely family in Kiev. Between 1015 and 1018, already preparing to become a monk, he was an escort of Predslava, the daughter of Vladimir I of Kiev.[1] In Kiev, he witnessed the assissination of the princes Boris and Gleb and had to find refuge with the sister of the future Prince Yaroslav I the Wise.[2]