Christianity, Judaism, Zoroastrianism, and the Sunni branch of Islam are officially recognized by the government, and have reserved seats in the Iranian Parliament. Historically, early Iranian religions such as the Proto-Iranic religion and the subsequent Zoroastrianism and Manichaeism were the dominant religions in Iran, particularly during the Median, Achaemenid, Parthian, and Sasanian eras. This changed after the fall of the Sasanian Empire by the centuries-long Islamization that followed the Muslim Conquest of Iran. Iran was predominantly Sunni until the conversion of the country (as well as the people of what is today the neighboring Republic of Azerbaijan) to Shia Islam by the order of the Safavid dynasty in the 16th century.