Alexander's alleged Wall against Gog and Magog, often connected with the enclosure of the apocalyptic people, was a widespread theme among Syriac Christians in Mesopotamia. In the ninth century Sallam the Interpreter dictated an account of his search for the barrier to the Arab geographer Ibn Khurradadhbih. The reliability of Sallam's journey from Samarra to Western China and back (842-45), however, has always been a highly contested issue. Van Donzel...