By 632 CE,
Yazdegerd III came to power in Persia but the
Arab/Muslim army had already begun
invading Persia. The Muslims
defeated them at
Nahavand and Yazdegerd was slain by a miller in
Merv in 652, bringing an end to the Sasanian dynasty and with it Zoroastrianism's history as the official religion of Iran. While losing their religion and script along with some Sasanian historiographical literature, the language and culture essentially survived. Between the seventh and thirteenth century, political and social pressures resulted in ascendancy of Iranian Muslim over the Zoroastrians. With the conquests, Iranians gradually lost their predominant religion. The Zoroastrians moved to India in successive migrations in the Islamic period. The initial migration following the conquest has been characterized as a religious persecution by invading Muslims. According to the account, the Zoroastrians suffered at their hands and in order to protect themselves and safeguard their religion, fled first to northern Iran, then to the
island of Hormuz and finally to India. This generally accepted narrative of migration emphasises Muslim persecution while identifying Parsis as religious refugees. Recently, scholars have questioned this explanation of Iranian origins. There is a scarcity of sources about the migration. Historians are forced to rely exclusively on
Qissa-i Sanjan written in 1599 by a Parsi Priest and
Qissah-ye Zartushtian-e Hindustan written more than 200 years later. This is complicated by the fact that there were already Zoroastrians in India in the Sasanian period. Iranian Zoroastrians are known to have been trading with India for centuries before the dates calculated for arrival of Parsis per
Qissa-i Sanjan. Ruksana Nanji and Homi Dhalla while discussing archaeological evidence for 'The Landing of Zoroastrians at Sanjan', conclude that the most likely date for the migration at the start of the middle phase of their chronology, namely the early-to-mid-eighth century. Nevertheless, they express their general skepticism about the Qissa-i Sanjan account. Scholar Andre Wink has theorized that Zoroastrian immigrants to India, both before and after the Muslim conquest of Iran, were primarily merchants, since evidence suggests it was only some time after their arrival that religious experts and priests were sent for to join them. He argues that the competition over trade routes with Muslims may also have contributed to their immigration. During this period, Zoroastrian traders faced execution outside India, including in
China where many were killed during the
Guangzhou massacre. The immigration of Zoroastrians to India continued, and by 1477 they had lost all contact with Persia. Not until three hundred years had passed would they come into contact. Zoroastrians also played a notable role during the
freedom movements of India. There were also subsequent migrations, especially resulting from attempts of
Safavids' to convert their subjects to
Shia Islam in the sixteenth century. This added to the Parsi population and cemented their close association with Iran. == Demographics ==