What are the essential 4 parts for a civilization to develop? explain how rivers
were the source of civilization?

One of the things that is important for a civilization to develop is a good geographic location, which is why most early civilizations were located near rivers, thus you have river valley civilizations because it had rich soil, good for planting, growing crops. Eventually many of the people starting living in permanent settlements (neolithic revolution). Rivers also brought monsoons, but also brought many floods. Many developed irrigation systems and canals, and made many other things.

Contributing factors  leading  to the harlem renaissance were the great migration of african americans to northern cities, which concentratedambitious  people in places where they could encourage each  other, and the first world war, which had created new industrial work opportunities for tens of thousands of people.