Clouds over Yazd.

Yazd (Persian: یزد‎)
The city was definitely a Zoroastrian centre during Sassanid times.
After the Arab Islamic conquest of Persia, people periodically faced extreme religious oppression including forced conversions, massacres, harassment, and other forms of discrimination, and then many fled to Yazd from neighbouring provinces. By paying a levy, Yazd remained Zoroastrian even after its conquest, and Islam only gradually became the dominant religion in the city.