Zoroastrian Dari (also referred to as 'Behdinani) is a varietal of Persian/Farsi/Dari spoken in central Iran. Sadly, this is an endangered language.  Parents are intentionally not transmitting it to their children, in favor of standard Persian.  They feel that their children will have an advantage in school and life if they only speak standard Persian.  

While primarily spoken in Iran, there is also a large Zoroastrian Dari speaking population in India; after the Islamic conquest of Persia (Iran), many Zoroastrians left the region for India.