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.

Andrei karlov was the russian ambassador