From the Bishop who oversaw the destruction:

"We found a large number of books in these characters and, as they contained nothing in which were not to be seen as superstition and lies of the devil, we burned them all, which they regretted to an amazing degree, and which caused them much affliction."

I can barely imagine the anguish those people must have felt. Imagine witnessing the destruction of your entire recorded history. Virtually all of the knowledge and art produced by the civilization wiped out in a single act.