User blog comment:Dragonzzilla/Assassin Idea/@comment-107.193.43.114-20130723194134/@comment-5546424-20130724011718

Assuming both the Assassins and Templars managed to spread across the Afro-Eurasian supercontinent before that time (or at the very least managed to reach Nordic countries during the time between 800 and 1050 AD), then it could theoretically have been possible for them to have reached the Americas before Christopher Columbus.

That is, of course, also assuming it isn't specifically said in the AC lore that neither faction reached the Americas until 1503...