Battle of al-Qādisiyyah
The Battle of al-Qādisiyyah (636 CE) and the Battle of Nihavānd (642 CE) were instrumental to the collapse of the Sassanid Empire and state-sponsored Zoroastrianism; destruction or conversion (mosques) of some fire temples in Greater Iran followed. The faith was practiced largely by the aristocracy but large numbers of fire temples did not exist. Some fire temples continued with their original purpose although many Zoroastrians fled. Legend says that some took fire with them and it most probably served as a reminder of their faith in an increasingly persecuted community since fire originating from a temple was not a tenet of the religious practice.