Hey there! I'm happy to help!
Water is of paramount importance in a society. It is needed hydrate the body and to grow crops. If there wasn't water everyone would die and therefore, no society. For this reason, ancient civilizations wanted to be as close to water as they can, usually in the form of a river. Here are some examples.
Nile⇒Egypt
Tigris and Euphrates⇒Mesopotamia
Yellow and Yangtze⇒China
Indus River Valley⇒ Indus River Valley Civilization
A city that is right next to water is going to be more successful than one that is far away from water. Keep in mind that back then, things like irrigation, water pipes, etc. were not in existence, so a civilization had to be extremely close to the water source so the citizens could utilize it. All in all, where there was water, there was most likely a developing city.
Have a wonderful day and keep on learning! :D