The shroud that suddenly turned up in the middle ages....
If you count the "middle ages" as being from 544 AD to 1202 AD, you might be right, since we have documentary evidence, including descriptions of the Shroud, of its being in Eddessa and Constantinople at various dates during those years. Certainly the writers of those documents thought they were in possession of the Burial Shroud of Jesus Christ which showed a faint image of the entire body of the Crucified Christ. It certainly was known and reported in history prior to the 1352 "first" exposition in Lirey, France. The break in the chain of custody between the sacking of Constantinople by the members of the 4th Crusade in 1204 and the Shroud's appearance in the possession of a descendent of one of the leaders of the 4th Crusade in (c)1348-1351 is the problem. Read the article... it gives a synopsis of the evidence.
This is sort of like saying that the Americas didn't exist before Columbus discovered them in 1492... ignoring all the subsequently found evidence of trade across the Atlantic and Pacific prior to Columbus. . .