[1] He was the only son of William I and inherited the entire county of Astarac, which had been reduced in area by partitioning among heirs in earlier generations.
[3] Between 1100 and 1110 Sancho, joined by his son Bernard and several other lords, donated land at Fonsorbes along with some other rights and revenues to the Church of the Holy Sepulchre and the Hospital of Saint John of Jerusalem:[7]
A certain Arnaud of Astarac joined Sancho on this occasion and donated Salvetat de Sainte-Foye to the Holy Sepulchre.
[8] The charter of donation was witnessed by Raymond II de Pardiac, who was the archbishop of Auch from 1096 to 1118/9.
Nicolas Guinaudeau dates it to around 1096,[2] but Helen Nicholson places it after the First Crusade (1096–99), when the Holy Sepulchre came under Christian control.