Having not seen the map before, and noting from https://en.wikipedia.org/wiki/Fra_Mauro_map it was apparently by a Venetian...

Is it known why the Italia peninsula and most of the surrounding area has been rubbed away over time while most of the rest of the map looks fairly untouched? (Bulgaria might have a slight issue, yet nothing like the entire country being smeared) Did not see anything mentioned in the Europe or summary portion of the above article.