Though it was once the majority and official religion of the Iranian nation, Zoroastrianism eventually shifted to the Indian subcontinent in light of the Muslim conquest of Iran, which saw the Rashidun Caliphate annex the Sasanian Empire by 651 CE.

The comparatively liberal atmosphere of India and the protection provided by historical Indian kingdoms to their Zoroastrian subjects enabled the religion to flourish outside of the Iranian plateau.

The Muslims defeated them at Nahavand and Yazdgird 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.

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.

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.

[5] 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.

In both of them their settlement is approved by the Rajah who addresses certain conditions for it: they would explain their religion, promise not to proselytise, adopt Gujarati speech and dress, surrender their weapons and only conduct their rituals after nightfall.

The Zoroastrian community in India remains one of the most recognized groups, playing a part in various commercial sectors such as industry, movies, and politics.

[citation needed] The long presence of the Parsis in the Gujarat and Sindh areas of India is supported by a genetic study[27] and it also distinguishes them from the smaller Zoroastrian Indian community of Iranis, who are more recent arrivals.

Although the term 'Irani' is first attested during the Mughal era, most Iranis are immigrants who arrived on the subcontinent during the 19th and early 20th centuries, that is, when Iran was ruled by the Qajars and when religious persecution of non-Muslims was rampant.