↑ See, for example, Bowersock, Glen Warren, Peter Robert Lamont Brown and Oleg Grabar Late Antiquity: A Guide to the Postclassical World (1999, Harvard University Press) p. 597, which notes that many of the details surrounding Muhammad's life as given in the biographies, are "problematic in certain respects, the most important of which is that they represent a tradition of living narrative that is likely to have developed orally for a considerable period before it was given even a relatively fixed written form. Ideally, one would like to be able to check such accounts against contemporary evidence... however, there is no relevant archaeological, epigraphic, or numismatic evidence dating from the time of Muhammad, nor are there any references to him in non-Muslim sources dating from the period before 632." Also cf. El-Cheikh, Nadia Maria Byzantium Viewed by the Arabs (2004, Harvard University Press) p. 5, "One major challenge to examining initial contacts between Byzantium and the early Muslim umma arises from the controversy surrounding the traditional Islamic account... ...sources are not contemporaneous with the events they purport to relate and sometimes were written many centuries later. These sources contain internal complexities, anachronisms, discrepancies, and contradictions. Moreover, many of them provide evidence of embellishment and invention that were introduced to serve the purposes of political or religious apologetic."
