Why did the neighboring community replace the clan community and why did inequality and the nobility appear?

Because the tribal community could not contain a huge number of people, which did not allow achieving any goals, and the neighboring community was happy with a large one and there was an opportunity to hunt for larger livestock, occupy most of the land. Inequality and nobility appeared, for example, due to the fact that some person has more fertile land, he is richer in some resources than another who has less fertile land.