I don't see why people care so much about the end of the world..
Like seriously, when you're dead.. you're not gonna be thinking "Oh shit, I shouldn't have died that day!"
When the time comes, it'll come. You can't do anything about it. You cant determine the dates of "Judgement days".. Hell, it's just a ploy to get your money.
History isn't a proof, unless you somehow go back in time and find the reason why the calendar stopped at whatever date.. In my opinion, the people from the past just got lazy and didn't feel like finishing it.