Zoroastrianism is the first monotheist religion and one of the world's oldest religion. It was the official state religion of Persian empire during centuries until the Muslim conquest of Persia. 

Followed years of harassment and most of  the Zoroastrians emigrated to India, where they are known as Parsis. 

Their traditions are now rooted in Iranian's such as Sadeh, a celebration which consists in lighting fire to celebrate the coming spring, and Nowruz, New Year's date.