He's seriously deluded. He believes that volumes of historical writings, C-14 dating, etc notwithstanding, that about a thousand years of recorded history never happened. Largely on the basis of the fact that the exponential population growth Europe has had since the British Agricultural revolution, if projected backwards in time, would say that there wouldn't have been as many people in Rome as there were.
Even a cursory understanding of, say, the trials our ancestors went through in the 1300s makes it obvious that he's wrong to project back his little exponential curve that far.
He's not the only grandmaster with some wacky ideas about history. Here's world #11, Alexander Grischuk, praising Joseph Stalin and discussing how 9/11 was a setup: http://www.whychess.org/node/514
Yep, he sure has some wacky ideas about history. Still, gotta give him credit for the fact that his wacky ideas are at least unusual -- he seems to have developed his stupid belief system for himself rather than acquiring it wholesale from someone else.
And yes, he's amazing at chess. However that is not necessarily an endorsement of his abilities at anything else. Paranoid delusions seem to be a significant occupational hazard at top levels of play. (See Bobby Fischer for a significant example.)
The brain is a pattern recognition engine well known to report many false positives. Most people are aware of that, be it often unconsciously. Chess masters learn to trust their intuition and pattern recognition, even when contrary signals are present, because, for some reason, that works in chess. It doesn't in the real world, where there are much more than 32 (the number of pieces) facts to keep track off.
