In my headcanon, there was a period a very long time ago when the Water Tribes were feared anywhere that was less than a few days march from an ocean or a navigable river, a la the aforementioned vikings, and even places like Caldera weren't entirely immune to being the targets of tribute demands or recreational freebooting.

(I'm envisioning sort of an eastern-flavored equivalent of the Sack of Paris, only with less guys named Charles the Bald.)

-Merc
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