What is the single most important factor that caused early humans to change over time from nomadic societies into city-states? 1: the Agricultural Revolution
2: the formation of governments
3: the development of cuneiform
4: the advancement of technology

1. the Agricultural Revolution

Explanation:

The reasons why early humans choose to be nomadic societies was because their main method of getting food at the time was through hunting.  After hunting in a certain area for a prolonged period of time, the numbers of animals will gradually depleted. This force the humans to move to another place with higher number of animal population.

After agricultural revolution, Humans get their foods mainly from growing crops. This enable them to stay in one place for a long period of time without having to fear that they wouldn't run out of food to eat.  After they had the ability to stay in one place, they started to managed their lands by forming city states.