Complex sentence: The Pope also authorized a crusade in the Iberian peninsula (modern Portugal and Spain), although the war against the Moors had been going on for hundreds of years, since the defeat of the Muslims at Covadonga in 718.
Split into simpler sentences: The Pope also authorized a crusade in the Iberian peninsula, where the war against the Moors had been going on for hundreds of years. The traditional start of the Reconquista is identified with the defeat of the Muslims at Covadonga in 718.