Upvote:-1
The Pseudo-Isidore is a case in point. Peter Heather has a very interesting account of it, in one of his books.
Upvote:5
Forgery was common in medieval time, beginning with the most famous one: the Donation of Constantine.
Very common objects of forgery were holy relics which were traded in great quantities. Europe was full of the itinerant merchant selling these relics.