アルル王国
William was the son of Bertrand of Baux, the first Prince of Orange a major patron of Occitan poetry, and Tibors de Sarenom, a sister of Raimbaut d'Aurenga and herself a trobairitz. In 1215 when the Emperor Frederick II sought to make his power effective in the Kingdom of Burgundy, he granted to William at Metz the whole "Kingdom of Arles and Vienne", probably referring to the viceroyalty of the kingdom. William was imprisoned in Avignon in the summer of 1216 and remained there until his death in June 1218. William's descendants continued to claim the Kingdom of Arles until 1393.