It's interesting that in Judaism, it's the opposite. Always moving in and then forcibly moved out. Abraham came from Ur (Mesopotamia), then Exodus from Egypt into Canaan, then Babylonian exile and back to Judea.

In myth-making, you've got to work with the established facts on the ground. It makes sense for China, India and Egypt to perpetuate the "always been here" mythology, but obviously for Jews being forcibly moved around and discriminated against is a given, so you build around that.

I have heard that the story of Moses was developed as way to unite the northern people Judah with the southern Israelites.

They needed a central story to unite the ideas.

I’m no expert but I think I have the theory straight.