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Hmm... well Sōgi was alive in the 15th century, so that was the first written story, but we don't know when people first started talking about it.

Nevermind. When I read this it reminded me of a similar story I heard in a UFO/Alien context. But in the meantime, I remembered that it was a Chinese story. Sadly couldn't find it, I saw that like three years ago. I vaguely remember that it was a story about a woman with incredible beauty that seems to never age, that came on a boat from an unknown origin. Haha, sorry can't remember much else.