Complex sentence: In the 10th century a massive conversion of Christians took place, and "muladies" (Muslims of ethnic Iberian origin), Arabs, and Berbers comprised eighty percent of the population of Al-Andalus by around 1100.
Split into simpler sentences: In the 10th century a massive conversion of Christians took place, and "muladies" (Muslims of native Iberian origin), formed the majority of Muslims. The Muladies, together with other Muslims, comprised eighty percent of the population of Al-Andalus by around 1100.