The Cycle of Magic, A Continuity Error? Options

[Semerkhet]

I've long been under the impression that the original Shadowrun authors based the cycle of magic on the Mayan calendar's Long Count. I based this mostly on the text of the speech given by Ehran the Scribe to the Young Elven Technologists, part of which is quoted on AH's site:

"As the last Age of Magic came to a close, the citizens of Atlantis began to disperse from their homeland, carrying their sophisticated technologies and culture to their new homes throughout the world. Only the magic of its inhabitants protected the isle from the forces of Nature, and the Atlanteans knew that as the level of magic in the world dropped, the day would come when their magical protections would fall and Atlantis would sink back into the depths from which it came. That day came on August 12th, 3113 B.C., marking the end of the Fourth World and the beginning of the Fifth."

This date corresponds nicely to the one given in the wikipedia article on the Mayan calendar, which places the starting point of the Long Count at August 11, 3114 (3113 if you use the astronomical calendar).

Then I came across the following sentence in The Darkest Hour, the most recent entry in the Dawn of the Artifacts series of adventures. I've stripped the context out of the sentence to avoid spoilers.

...including the destruction of Atlantis in 9,564 B.C.

What's going on here? Is this just really sloppy continuity editing or is something else going on? Has there been some sort of revisionist history going on and the developers decided that the period of the "cycle of magic" needed to be longer?