The Disputed Sabians

Taken from an article about Harran

At the beginning of the Islamic period Harran was located in the land of the Mudar tribe (Diyar Mudar), the western part of northern Mesopotamia (Jazira). Along with ar-Ruha' (Şanlıurfa) and Ar-Raqqah. It was one of the main cities in the region. During the reign of the Umayyad caliph Marwan II Harran became the seat of the caliphal government of the Islamic empire stretching from Spain to Central Asia.

It was allegedly the Abbasid caliph al-Ma'mun who, while passing through Harran on his way to a campaign against the Byzantine Empire, forced the Harranians to convert to one of the 'religions of the book', meaning Judaism, Christianity, or Islam. The pagan people of Harran identified themselves with the Sabians in order to fall under the protection of Islam. Aramaean and Assyrian Christians remained Christian. Sabians were mentioned in the Qur'an, but those were a group of Gnostic Mandaeans living in southern Mesopotamia. The relationship of the Harranian Sabians to the ones mentioned in the Qur'an is a matter of dispute.