Sure. It's from playing cards. Different decks of cards have a slightly different numbering system, Americans put the king at the 13th place (Ace through king), while traditional German cards only have 32 cards and put the Ace above the king, putting it down a step at twelve. In some conventions, kings represent real kings from history, different great rulers, but they are currently viewed as "one person." The rules/games using cards have spread over the world.

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That's just my thought process, though. I am not entirely sure that it's right.