Philip was born in or near Pavia in the Imperial Kingdom of Italy as the tenth child and eighth (but fifth and youngest surviving) son of Frederick Barbarossa, King of Germany and Holy Roman Emperor and his second wife Beatrice I, Countess of Burgundy. His paternal family was the noble House of Hohenstaufen, the name given to the dynasty by historians since the 15th century. The origins of the family are still unclear today; the ancestors on the paternal side were minor nobles and their names have not been preserved. All that is known about Barbarossa's great-grandfather Frederick von Büren is that he married a woman named Hildegard (whose own parentage was disputed: she was a member of either the Comital family of Egisheim–Dagsburg or the obscure Schlettstadt family). A few years ago it was assumed that the Schlettstadt property did not belong to Hildegard but to her husband himself and the Hohenstaufen were therefore not a Swabian but an Alsatian family. It wasn't until around 1100 that the family under Duke Frederick I of Swabia located into the East Swabian Rems valley.