In his youth Bela III, king of Hungary (1172-1196) lived in Constantinople as the betrothed of the emperor Manuel Comnenus' daughter and was appointed to be heir to the Byzantine throne. There he was called Alexius probably owing to an oracle, according to which Manuel's successor's name would start with the letter alpha. However, when a son - also named Alexius - was born to Manuel, he had him crowned co-emperor and had the betrothal of Bela and Maria dissolved on the pretext of a ruling of the 1166 Synod of Constantinople, which banned marriage between relations by marrige to the seventh degree. It is this ruling that is referred to in a sentence in Cinnamus, which has been ignored this far because of the assumption that Bela and Maria were related in the eighth degree. As a matter of fact, they were related in the seventh degree by the marriage of the Hungarian king Stephen IV and Maria Comnena, daughter of Isaac Sebastokrator.