The correct answer to this open question is the following.
You did not attach the map. Without that information, we do not know what you are referring to.
What we can do is to comment on the following general terms.
The most direct factor that contributed to the spread of settlement depicted on the map in ancient civilizations, if that is what you are referring to, was conquering. Empires started to grow, gain power, and were ambitious and decided to battle other regions and towns to conquer them and gain those territories to form empires.
For instance, there is the example of Sumeria. They established powerful city-states such as Lagash, Nippur, Eridu, Kish, or Ur, and they first traded, then fought to increase their power and dominion, and spread their territories.
