Original: In 1212 Muhammad III, "al-Nasir" (1199–1214), the successor of al-Mansur, after an initially successful advance north, was defeated by an alliance of the four Christian princes of Castile, Aragón, Kingdom of Navarre and Portugal, at the Battle of Las Navas de Tolosa in the Sierra Morena.
Simplified: But by 1212 Muhammad III, "al-Nasir" (1199–1214) was defeated by an alliance of the four Christian princes of Castile, Aragón, Kingdom of Navarre and Portugal, at the Battle of Las Navas de Tolosa in the Sierra Morena.