Gadara, located some 120 km northwest of Amman (Photo courtesy of ACOR) AMMAN — The Abbasid presence at Gadara (modern Umm Qais) was mentioned in the works of Arab mediaeval geographers and scholars.

Van Berkel, a specialist in the Abbasids’ empire, recalls that the City of Peace, as it was called, had probably around half a million inhabitants. “But that’s still gigantic and beyond ...