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 end of Zoroastrianism as Persia's state religion came in stages rather than a single defeat. Arab Muslim armies first attacked Sasanian territory in 633, and permanent Sasanian resistance west of Iran was broken three years later at the Battle of Qadisiyyah in 636. The conquest of the empire was not complete until 651, when the last resistance fell and more than four centuries of Zoroastrianism as Persia's official state religion came to an end.
The religion itself did not vanish with the state that had sponsored it. Conversion of the Persian population to Islam was gradual rather than immediate, unfolding over generations rather than in the years immediately after 651, and Zoroastrianism went on surviving as the faith of a shrinking minority for centuries afterward, its communities persisting under new rulers who no longer shared its beliefs.
What ended at the conquest was not the religion but the state apparatus behind it. The same structure that had sponsored the Avesta's formal compilation under Shapur II and enforced Zoroastrianism's religious authority across Sasanian territory did not survive 651, even though individual believers and communities did. What had been an official state religion for more than four hundred years became, from that year onward, the faith of a minority living inside someone else's empire, a demotion in political standing far more abrupt than the community's own long, gradual decline in numbers that followed it.