Zoroastrians / Zerdeshtiti
Zoroastrianism is the religion and philosophy based on the teachings ascribed to the prophet Zoroaster (Zarathushtra, Zartosht).
Mazdaism is the name of the religion that acknowledges the divine authority of Ahura Mazda,
proclaimed by Zoroaster to be the one uncreated Creator of all (God).
As demonstrated by Zoroastrian creed and articles of faith, the two terms are effectively synonymous.
In a declaration of creed - the Fravarane - the adherent states: "profess myself a devotee of Mazda, a follower of Zarathushtra.."(Yasna 12.2,12.8).
It was a state religion of Persia until the decline of the Ssassanids and gradual Islamization.
In modern Iran, the Zoroastrians face acute discrimination, although Islam includes them among
"people of the book" and one seat in the Iranian parliament is allocated to the Zoroastrian representative.
There is only about 20.000 of them left in Iran, 70.000 Parsi Zoroastrians in India, 5.000 in Pakistan, 2.000 in Azerbaijan,
and a few in Afghanistan and Central Asia and about 25.000 in North America.Note that this flag has another version which you can find in this [link]