40% in the mid 9th century to close to 100% by the end of 11th century.[14] Islam was readily accepted by Zoroastrians who were employed in industrial and artisan positions because, according to Zoroastrian dogma, such occupations that involved defiling fire made them impure.[15] Moreover, Muslim missionaries did not encounter difficulty in explaining Islamic tenets to Zoroastrians, as there were many similarities between the faiths.