Among the kings of the Árpád Dynasty King Saint Stephen belongs to the few, whose year of birth was noticed by the sources. According to the Chronicle-composition from the 14th century he was born in 969, according to Simon of Kéza in 967, according to the Polish sources in 975. A late author from the 15th century, Petrus Ransanus writes, that Stephen was 63 years old, when he died. Since Stephen died in 1038, the date reported by Ransanus could support the authenticity of the year of birth in 975. But Ransanus is contraversial, because according to him Stephen was born in 969: the author of Italian descent must have incorporated many different works in his own, and did not dissolve the contradictions.
In Hungarian historiography there are historians who accept either 969 or 975, but there are some, who discard all versions, and build up a further theory. Stephen could marry Gisela about 996. According to an interpretation it is improbable, that he was born in 969 or 975, because if he did, he would get married too late in 996, and would be too old in 1038 when he died.
In my study I give an outline about the difficulties of determining the date of birth of different European rulers – e. g. Charles the Great, Alfonso VI. of Castile and Leon. A conclusion can be deduced from the overview: the exact date of birth of rulers even in Western Europe is not without problems. It is not unpredecented in the medieval Western Europe that a ruler died at the age of 60 or almost 70 years. There is an example for the approximately late marriage too.
I try not only to answer the question when King Saint Stephen was born. I ask the question why different sources give different dates for his birth. If one of the authors was wrong, how his mistake can be explained. I set up a hypothesis how the author of the Chronicle-composition could calculate the date 969 and the authors of the Polish sources the date 975, but there can be arguments against my assumption.
According to the Chronicle of Zagreb the year of birth of Saint Stephen could be put at the second half of the 970s. The above mentioned report of Ransanus that the king was 63 years old when he died has to be considered more seriously.