Zoroastrianism was the state religion of Iran for roughly 1,300 years, from the Achaemenid Empire (6th century BCE) to the fall of the Sasanian Empire in the mid-7th century CE, though the religion itself originated earlier and continued after the Arab conquest. The religion first gained official status under the Achaemenids, becoming the prevalent religion, and remained so through the Parthian and Sasanian empires. After the 7th-century Arab conquest of Persia, Zoroastrianism became a minority faith due to Islamization and persecution.