Why did Christians in al-Andalus live in mountainous areas?

Answer 1

711 was a key year in Spanish history. It was the year when Muslim (or Moorish) forces crossed the straits of Gibraltar, defeated a Visigothic army somewhere west of Gibraltar, and moved quickly northwards. Within a few years, they had conquered almost all of the Iberian Peninsula, and Christian Visigothic Hispania was transformed into Muslim al-Andalus (as the Muslims called the land they occupied). Politically, the transformation was done rapidly, but the change from Christianity to Islam --the new religion that accompanied the Moors- and the social changes that followed took longer.

The newcomers did not impose their religious beliefs on the Hispano-Visigothic Christians and did not insist on conversion (those who did convert were known as Muwallads, literally "those born of two races"). Those Christians who did not flee to the mountainous north but signed agreements with the Moors were allowed to keep their property and retain their faith. Still, these agreements did not come without cost: the Christians were required to pay certain taxes and to recognize the superiority of Islam as the last and final revelation from God. Together with the Jews -who were long established in the peninsula-- these remaining Christians communities in al-Andalus were granted the status of dhimmis because both Christianity and Judaism shared with Islam a common bond as descendants of Abraham. As dhimmis, both Christian and Jews enjoyed largely the same rights; the following paragraphs, however, are restricted to the Christians of al-Andalus.

Answer 2

Christians in al-Andalus typically lived in the mountains because it was harder for the tax authorities to find them. In al-Andalus, Christians had to pay a special tax to continue to worship in al-Andalus. As a result, if the tax authorities could not find them in the mountain, they could not collect the taxes.

Additionally, the Christians in Asturias (which was one of the Christian Kingdoms that was never overrun by the Muslims) survived because the mountains of Asturias posed an incredible impediment to the typical style of Amazigh and Arab Warfare which was based on the use of a powerful cavalry.