This is when my mind links a particlar myth of both cultures and more about a fish man showing up and teaching people the ways of civilization. As I remember it

This is when my mind links a particlar myth of both cultures and more about a fish man showing up and teaching people the ways of civilization. As I remember it was Mesopotamia, China, and the Indus valley, and maybe a few more? I think its plausible that civilization itself spread via sea faring peoples, so perhaps it was some hyksos like people that brought not their genetics, but knowledge.