Practically the entire Anglo-Saxon period in England took place during the “missing” years. Speaking of England, there’s another loony out there who maintains that, when Caesar invaded, the people were already speaking Modern English, Old English, not to mention British (ancestor of Welsh and Cornish) being just part of the Evil Conspiracy, I guess.
It’s Fomenkoism that really scares me, though. His basic thesis is that the entire ancient and medieval world was created out of the air by evil Jesuits, to conceal the fact that everything told about Jerusalem and about Rome really happened in Moscow (which conveniently makes the Russians into, more or less, Herrenvolk), and, Russia being in the state it’s currently in, the idea’s caught fire, with serious attempts being made to mandate it being taught in the schools.