His parentage is unknown, but onomastics and chronology indicate that he may have been a son of Lupus II.
Ermoldus Niger celebrates him in a poem as a nutritus of Charlemagne, perhaps indicating that he was raised at the Frankish king's court.
[4] This has led to speculation that he was initially sent by Charlemagne to pacify the Gascons and be their duke: a royal Frankish appointee.
[5] He was the probable elder brother of Lupus Centule, Seguin I, and Garsand (García) and father of Aznar and Sancho II.
Sancho died on an unknown date before 812 and was probably succeeded by his brother Seguin.