In the year 639 or 640, the city fell to the Muslim conqueror Iyad ibn Ghanm. Since then, it has figured in Arabic sources as ''al-Raqqah''. At the surrender of the city, the Christian inhabitants concluded a treaty with Ibn Ghanm that is quoted by al-Baladhuri. The treaty allowed them freedom of worship in their existing churches but forbade the construction of new ones. The city retained an active Christian community well into the Middle Ages (Michael the Syrian records 20 Syriac Orthodox (Jacobite) bishops from the 8th to the 12th centuries), and it had at least four monasteries, of which the Saint Zaccheus Monastery remained the most prominent one. The city's Jewish community also survived until at least the 12th century, when the traveller Benjamin of Tudela visited it and attended its synagogue.