Iran has an ancient history and was invaded by mohammedans a few hundred years ago (can’t remember dates) but Bill Warner knows all the history of the Islamic invasions. Iran was Zoroastrian for a couple thousand years but they were forcibly converted or killed in order to turn the country mohammedan. Even now there are Jews, Christians and Bahais there, for starters. Some Zoroastrians went to India and are now called Parsees.
The lands now called Iran have been under Islam to various extents from about fifteen years after Muhammad showed up. Some were Arabs, some Mongol, some Turks, all Mohammedans about 1500 years. Some were hardcore and proselytized some gov’ts didn’t. The non-Muslim pay the jizya.