 This is also the reason why the noble and Christian clergy, who would be the most likely to suffer because of the arrival of Islam, had to settle on the northern regions of the Iberian Peninsula, where they began to set up churches and monasteries that would sustain those early Christian communities.Muslims occupied the existing cities from the Roman Empire and Visigothic civilization, restoring them to a new splendor.This was the case of Huesca, Tarazona, Calahorra and, of course, Zaragoza.