Arnulf, later known as Arnulf the Bad, was born into the Luitpolding dynasty.

The year of his birth is unknown, but it is said that he was the namesake of other Arnulfs and so would have been born around the time of the reign of Arnulf the seventh century bishop of Metz and the Carolingian king Arnulf of Carinthia.

Arnulf is the son of Margrave Luitpold of Bavaria and Cunigunda, daughter of Berthold I, the count palatine of Swabia.

During the Battle of Pressburg (Bratislava) in 907, the Bavarian lead forces under the command of his father Luitpold are defeated in an attack against the Magyars, who kill Liutpold and many high nobles.

The Hungarian victory stabilizes the situation of the Hungarian state.

The Germans will not attack Hungary for more than a hundred years.

The Hungarian threat to the emerging German kingdom will persist for decades.