Where Am I?

CLUES

1. Ibadi Muslims established a community in this region in the 10th century.
2. Five fortified villages, or ksour, constitute walled citadels that contain a mosque surrounded by houses built in concentric circles.
3. Mosques here were conceived as fortresses. They served as watchtowers and included arsenals and grain storage.
4. The settlements have influenced Arab architecture and planning for nearly 1,000 years.

ANSWER  M’Zab Valley, Algeria