Religion

time to understand things like geology. Their lives were always controlled or effected at least by someone or something. Their current leader, other tribes leaders, the leader of a herd on animals they hunted, many things. It would seem logical that the weather, earthquakes, eclipses, must be controlled or made to happen by someone or something.

Once they invented what would be called gods, then it was better than the rules coming from any new leader, just because they could, and could enforce them. You ended up with a set of laws that lasted that way.