 Since the Battle of Las Navas de Tolosa in 1212 halted the advance of the Almohads in Spain, a series of truces had kept Castile and the Almohad dominions of al-Andalus more-or-less at peace.However, a crisis of succession in the Almohad Caliphate after the death of Yusuf II in 1224 opened to Ferdinand III an opportunity for intervention.The Andalusian-based claimant, Abdallah al-Adil, began to ship the bulk of Almohad arms and men across the straits to Morocco to contest the succession with his rival there, leaving al-Andalus relatively undefended.