Research Question

What stories/historical events have lead us to the prediction that the world will end in 2012?

I am considering writing about 2012 because it is a strange topic.  There are many different stories out there, most probably made up by random people, about how and why the world will end in 2012.  I have briefly heard different stories of how people say it will end (meteors crashing on earth, volcanic ash causing an ice age, etc.) but I don't know where these ideas came from.  I would like to research and see what sort of historical events have lead to this prediction and see if there could be any truth behind it.  I don't know much about the topic, and honestly don't believe that the world will end in 2012, but i still think it is an obscure topic with lots of scepticism and debate over it which I could use for evidence.  I would most likely research and only include the stories/scenarios that are commonly repeated throughout sources in order to try and weed out the truly insane people.