<P> For at least under Rashiduns and early Ummayads, the administrative system of the late Sassanid period was largely retained . This was a pyramidal system where each quarter of the state was divided into provinces, the provinces into districts, and the districts into sub-districts . Provinces were called ustan (Middle Persian ostan), the districts shahrs, centered upon a district capital known as shahristan . The subdistricts were called tasok in Middle Persian, which was adopted as tassuj (plural tasasij) into Arabic . </P> <P> After the Muslim conquest of Persia, Zoroastrians were given dhimmi status and subjected to persecutions; discrimination and harassment began in the form of sparse violence . Zoroastrians were made to pay an extra tax called jizya, failing which they were either killed, enslaved or imprisoned . Those paying jizya were subjected to insults and humiliation by the tax collectors . Zoroastrians who were captured as slaves in wars were given their freedom if they converted to Islam . </P> <P> Muslim leaders in their effort to win converts encouraged attendance at Muslim prayer with promises of money and allowed the Quran to be recited in Persian instead of Arabic so that it would be intelligible to all . 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 . Moreover, Muslim missionaries did not encounter difficulty in explaining Islamic tenets to Zoroastrians, as there were many similarities between the faiths . According to Thomas Walker Arnold, for the Persian, he would meet Ahura Mazda and Ahriman under the names of Allah and Iblis . In Afghanistan, Islam was spread due to Umayyad missionary efforts particularly under the reign of Hisham ibn Abd al - Malik and Umar ibn AbdulAziz . </P> <P> There were also large and thriving Christian and Jewish communities, along with smaller numbers of Buddhists and other groups . However, there was a slow but steady movement of the population towards Islam . The nobility and city - dwellers were the first to convert . Islam spread more slowly among the peasantry and the dihqans, or landed gentry . By the late 10th century, the majority of the Persians had become Muslim . Until the 15th century, most Persian Muslims were Sunni Muslims, though today Iran is known as a stronghold of the Shi'a Muslim faith, recognizing Islam as their religion and the prophet's son in law, Ali as an enduring symbol of justice . </P>

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