13 (thirteen) is a natural number after 12 and before 14.
As everybody knows, 13 is regarded as the most unlucky number throughout the world(Except for a few). I was pretty eager to know about these as I was born on 13 of a month.On analyzing, it was found that an old story has been associated with this(As always a myth is associated with all these crap). It happened in Spain in the so called Before Christ period(the period where no history needs to be proved). In those periods all the kings of large dynasties had a common name followed by a roman number(Like Louis of France or the Edwards of England). Since, the common name is not that important in the context of the story, lets assume they were named King Arbit I,II etc.
Our Hero ( for some commercial essence) of the story is Mr.King Arbit XIII(13), who ruled over 13 cities with an army strength of 13000 and his that was 13 inches.I meant his foot. His only aim in life was to marry the daughter of another dynasty's king, King Arbito XIII (Since this common name too is irrelevant to the context of the story but a differentiation has to be made).
As usual, to marry a king's daughter they used to have some stupid games (which has been changed to mind games these days) and the winner "takes it all" type. Similarly here, it was a card game called Rummy (a game played with 13 cards each). And, our king with the sole aim of marrying her (those days this was the only job for kings unless ofcourse a war happened) decided to get into the groove.
Unfortunately,for our king there was no Wikipedia and hence no reference to rummy, lost badly like an Indian Olympic swimmer. Since, his only aim in life wasn't possible anymore (as there were no adidas taglines those days), our king killed King Arbito XIII, her daughter and then committed suicide. This information reached the dynasty which suggested "Our King lost in rummy because of the XIII card" (the obvious reason being, to hide the fact that he did not know how to play the game from the future generations). This information ultimately reached the people as "The King lost since the game was played with 13 cards".
And as generations passed, this information came into history as "In Dynasties such as Arbit and Arbito, XIII Kings were brutally killed by destiny". And whatever bad happened involving 13 was considered a continuation of this theory. So, like our cricketers blaming the pitch for their failures, the number 13 was accused for a ridiculous happening in history.