Jack Markwardt presented a paper, Ancient Edessa and the Shroud: History Concealed by the Discipline of the Secret, at the Ohio State conference in 2008:
Modern sindonology, drawing substantially upon the Mandylion Theory,1 appears to have established, within a reasonable degree of certainty, a substantial portion of the medieval biography of the Turin Shroud,2 commencing with its historical debut, between 5443 and 569,4 as the Image of Edessa; however, the relic’s whereabouts during the Missing Ancient Centuries, the half-millennium spanning its disappearance from Christ’s tomb to its reappearance in sixth-century Edessa, remain the subject of debate.
The author’s 1999 hypothesis,5 that the Shroud was taken, in apostolic times,6 to the Syrian city of Antioch, concealed and lost in 362,7 rediscovered in ca. 530,8 and conveyed to Edessa9 when Antioch was destroyed in 540,10 is supported by historical records which evidence the presence of a Christ-icon in both fourth-century Syria and sixth-century Antioch.
Useful perspective, perhaps, in light of the Edessa conversations of the past two days.