The "Corónicas" Navarras name "al yfant don Pedro, rey d'Aragón, et al marqués de Provença don Alfonso, et a don Ferrando, abbat de Mont aragón, et una filla que casaron en Ongría" as the children of "el rey don Alfonso d'Aragón" and his wife. The Gestis Comitum Barcinonensium names "Petrus…Alfonsus" as the oldest two of the three sons of "Ildefonsi", specifying that Pedro succeeded his father in "regnum Aragoniæ et Comitatus Barchinonæ, Bisuldini, Cerritaniæ et Rossilionis, ac Palearensem". The Crónica de San Juan de la Peña names "Pedro…Alfonso…y Fernando" as the three sons of King Alfonso II.
He succeeded his father in 1195 as PEDRO II "el Católico" King of Aragon, Conde de Barcelona, Gerona, Osona, Besalú, Comte de Cerdagne/Cerdaña et de Roussillon. He was crowned at Rome by Pope Innocent III . He received possession of the County of Urgel 1209 on the death of Armengol VIII without male heirs, in return for guaranteeing the rights of his daughter (to whom King Pedro’s son Don Jaime was betrothed). He vanquished the Almohades at Las Navas de Tolosa 1212.
He was defeated in battle by Simon de Montfort. The Annales Compostellani record that “Petrus Rex Aragoniæ” was killed “a Gallis apud Castrum…Muret II Id Sep” in 1213. The Crónica de San Juan de la Peña records the death in 1214 of Pedro II King of Aragon aged 40 years and his burial "en el monasterio de Sijena". 1