The first troubadour, whose songs are preserved, was as duke of Aquitaine the most important French prince around 1100. His military activity was, at least three times, directed against the Muslims. Her aunts and sisters were married to Iberian Christian kings, whom he defended against Almoravid invasion. In 1100-1102, he participated in Holy Land to a failed crusade. During these expeditions, he had several contacts with Arab courts, in particular with Imâd al-Dawla, the last emir of Saragossa of Banu Hudi dynasty, expelled of his capital by Almoravids. They were together in the troupe of the king of Aragon fighting them in Cutanda battle (1120). Imâd gave to him the so-called “Vase d’Aliénor d’Aquitaine”, his grand-daughter. It was preserved in Saint-Denis abbey and is nowadays in Louvre Museum. This precious crystal and silver object is not the only gift William IX received from a Muslim prince. At least one of his poems (V, Pasero ed.) seems to contain some Arabic words. Other elements show a possible influence of Hispanic-Arabic poetry in his own work. They nourish the debate on the ‘origins’ of Courtly Love. ‘Origins’ is not probably the good word, but better ‘polygenesis’ or Michel Foucault’s ‘conditions of possibility’. Thus, the study of the relations between William IX and Islam has to be done in an interdisciplinary way, which takes account of political and social history, of art history or of literature and linguistics.