Teh internets have spoken. A blog post over at TinyCatPants alerted me to the possibility that part of the early medieval period, specifically 614-911, never happened. Apparently, the whole ball of wax--Charlemagne, King Alfred the Great, the sack of Lindisfarne--was cooked up by Otto III and Gerbert of Aurillac (Pope Sylvester II).
Now, Gerbert was believed to have some pretty special powers, like being able to summon demons, foretell the future, and discover buried treasure, and he was also thought to have a swanky brazen head that whispered secrets to him, but inventing an entire three centuries? Hmm... On the other hand, I recently learned, in the course of a sustained research project, that Gerbert--diabolical communion aside--was a straight-A student in mathematics and astronomy. He probably had the chops to forge the calendar.
My question is: Why 614-911 specifically? It covers the lifetimes of Gerbert and Otto (and Otto's father and grandfather) and allowed Otto, as Holy Roman Emperor, to invent a fabulously powerful imperial predecessor. Isidore of Seville loses the last few decades of his lifetime (bummer) and Bede and Alcuin never existed at all?
But although this conspiracy theory is fantastically far-fetched, it does echo some of the wilder legends from the Middle Ages (see above: Gerbert). And forgeries--of documents and holy relics--were rampant. So maybe it all kind of fits together...