This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Muslim Conquest of Persia ended the Sasanian Empire's own status as the region's Zoroastrian state power after nearly four centuries of continuous rule. Zoroastrianism's subsequent centuries-long decline across Iran, from the dominant religion of a great state to a minority faith practiced by a shrinking community, is traced by historians in substantial part to this conquest and its long aftermath, though conversion to Islam across Iran was itself a gradual process spanning centuries rather than any immediate consequence of the military campaign alone.
Historians frequently contrast this conquest with the earlier Levant campaign, because, unlike Byzantine Syria, no rival imperial power survived anywhere in the region to contest the caliphate's new rule once Yazdegerd's own court had fled and fallen. That left Persia's political future fully bound to the Islamic world from this point forward. The conquest also brought a significant transfer of Sasanian administrative and courtly practice into the young caliphate's own governance, a legacy that outlasted the religious transformation it had accompanied.