a rebellion occurred during the "reconquista", the centuries-long conquest of muslim territories in the iberian peninsula (called al-andalus by the muslims) by christian kingdoms from the northern part of iberia. islam had been present in iberia since the umayyad conquest in the eighth century. at the beginning of the twelfth century, the muslim population in the peninsula was estimated to number up to 5.6 million, among whom were arabs, berbers and indigenous converts. in the following centuries, the christian kingdoms steadily grew in strength and territories while the muslim ones declined. the early thirteenth century was a period of great loss for the muslims. the almohad caliphate, which had dominated the muslim iberia, fell into dynastic struggles after yusuf ii died in 1224 without heir. al-andalus disintegrated into multiple small kingdoms or "taifas". meanwhile, ferdinand iii united the christian kingdoms of castile and león in 1231, and taking advantage of the muslims' disunity, conquered various territories in the south. his conquests during this period included the guadalquivir basin (also known as lower andalusia) and murcia, which became the principal centers of this rebellion.