Islamization of Iran

The Islamization of Iran began with the Muslim conquest of Iran, when the Rashidun Caliphate annexed the Sasanian Empire. It was a long process by which Islam, though initially rejected, eventually spread among the Persians and the other Iranian peoples. Although Arabization was a common element of the early Muslim conquests, it did not have as significant of an impact in Iran as it did elsewhere, as the Iranian populace persisted in maintaining many of their pre-Islamic traditions, such as their language and culture, albeit with adaptations to conform to the nascent religion. A distinctly Iranian Muslim identity emerged in this context and later sidelined the Arabs in what is known as the Iranian Intermezzo.

Iranian society was deeply transformed by the spread of Islam, which greatly influenced the nation's cultural, scientific, and political structure; the blossoming of Persian literature, philosophy, medicine, and art became major elements of Islam in Iran. Integrating a heritage of thousands of years of civilization and being at the "crossroads of the major cultural highways" in the Near East contributed to the Iranians emerging at the forefront of the Islamic Golden Age under the Abbasid Caliphate.

Between the 7th century and the 16th century, Sunni Islam was dominant among the Iranians, but this changed with the Safavid conversion of Iran to Shia Islam, which marked another historic societal shift for the nation. Consequently, Shia Islam remains dominant in modern-day Iran, where it is the official religion, as well as in Iraq and Azerbaijan.

After the Muslim conquest of Iran, during the 90-year-long reign of the Umayyad dynasty, until the time of Abd al-Malik ibn Marwan, the divan was dominated by the mawali and accounts were written using the Pahlavi script. The controversial Umayyad governor Al-Hajjaj ibn Yusuf forced all the mawali who had left for cities, in order to avoid paying the kharaj tax, to return to their lands. He was upset at the usage of Persian as the court language in the eastern Islamic empire, and ordered that it be changed to Arabic.

There are a number of historians who see the rule of the Umayyads as setting up the "dhimmah" to increase taxes from the dhimmis to benefit the Arab Muslim community financially and by discouraging conversion. Islam, during the Umayyad Caliphate, was initially associated with the ethnic identity of the Arab and required formal association with an Arab tribe and the adoption of the client status of mawali. Governors lodged complaints with the caliph when he enacted laws that made conversion easier, depriving the provinces of revenues. Notable Zoroastrian converts to Islam included Abd-Allāh Ibn al-Muqaffaʿ, Fadl ibn Sahl and Naubakht Ahvazi.

Patrick Clawson states that "The Iranians chafed under Umayyad rule. The Umayyads rose from traditional Arab aristocracy. They tended to marry other Arabs, creating an ethnic stratification that discriminated against Iranians. Even as Arabs adopted traditional Iranian bureaucracy, Arab tribalism disadvantaged Iranians."

The Arab conquerors, according to many historians, formed "a ruling aristocracy with special rights and privileges, which they emphatically did not propose to share with the mawali". Some rulers, such as Hajjaj ibn Yusuf even went as far as viewing the Mawali as "barbarians", implementing harsh policies such as branding to keep the subjects in check.

The case of Hajjaj is particularly noteworthy as many reports have come down to us from his racial policies and iron tactics in governing the provinces. And yet many skeptics point to the fact that some of these reports were written by Abbasid era writers who may have had a skewed view of their predecessors.