I don't think its far fetched at all. Stories and concepts have travelled, been adopted by disparate cultures throughout history. Look at the Epic of Gilgamesh where it talks of a Great Flood, where'd you hear that before? And Moses, lived in Egypt and exported monotheism, first HISTORICALY introduced in Egypt by Ahkenaton. It makes perfect sense to me for those who're looking to gain influence in a dominant culture to learn, adapt and adopt its stories, superstitions, etc and make it part of their own or create something new. Remember, back in those days most day to day information was via word of mouth, ever play Chinese Whispers?