I may be mistaken, but I thought the Fayum was located in an area near the Nile delta. If this is so, it would not be dry or conducive to preserving papyrus or anything organic. This is why the royal burials and other great caches of mummified remains have been concentrated in Upper Egypt.
[When the Muslims conquered Alexandria their leader said that anything written that was worthwhile was in the Koran. Everything else that wasn't in the Koran wasn't worth keeping.]
How WONDERFUL!