Complex sentence: The first permanent settlers on the Rock were the Moors, Muslims who arrived from North Africa in the beginning of the eighth century and used the area as a base from which to launch an invasion of the rest of the Iberian Peninsula.
Split into simpler sentences: The first permanent settlers on the Rock were the Moors, Muslims who arrived from North Africa in the beginning of the eighth century. They used the area as a base from which to launch an invasion of the rest of the Iberian Peninsula.