The people of Gerash were native Persians following the Zoroastrian faith before converting to Shia Islam in the 5th century of Hegira (11th century AD) by Amir Mohi al-Din Ibn Amir Qotb al-Din Ibn Amir Rooh al-Din, a direct descendant of Muhammad, and an aide of Afeef-Addeen Al Musawi, to whom the conquest of certain areas in the South of Iran by Arab Muslim warriors is attributed. It is known that Afeef-Addeen left Hijaz (in present-day Saudi Arabia) along with warriors from two tribes from Medina, namely Hawazin Bani Al-Muntafiq and Banu Tamim, and set for the conquest of the Persian South; areas that, due to their dry conditions and mountainous array, had remained immune to the Islamic conquests during the second Caliphate's time. Prior to its conversion to Islam, Gerash was ruled by a Zoroastrian leader by the name of Sarem Khoora (Persian).