The Codex Boturini is simultaneously an utterly unique “new original” and part of a series of copies of the migration tale without a known original.
The Mexica migration story was told and retold in at least ten pictorial codices and ten textual sources (Boone 1999:121-122).The Codex Boturini, produced in the first half of the sixteenth century, is itself likely a copy of an earlier, pre-Columbian version of the tale. Of course, we are only aware of the versions that survived in libraries and collections for five centuries. There were, presumably, many more.