Complex sentence: King Alfonso II of Asturias (Northern Spain) dies after a 50-year reign, in which he undertook numerous campaigns against the Muslim armies of the Umayyad Emirate of Córdoba, and allied himself with the late Charlemagne.
Split into simpler sentences: King Alfonso II of Asturias (Northern Spain) dies after a 50-year reign. He has undertaken numerous campaigns against the Muslim armies of the Umayyad Emirate of Córdoba and allied himself with the late Charlemagne.