Let's start with Sparta, because it clearly shows how a highly disciplined, military-style city-state formed in the Greek world.

Why did society become so military-focused, and how was it different from other city-states?

Order, discipline, and constant readiness were at the center, because strength and defense formed the basis of the Spartan state.

And if we look at the city-states, how does Athens or the development of other Greek poleis connect to this?

Here it becomes clear that the foundation of the Greek world was city-state autonomy, and within that, very different political and social models emerged.

So Sparta represented military order, while other city-states were much more open?

Exactly. Sparta centered discipline and military education, while in other poleis trade, politics, or community life played a bigger role.

Does that mean there were not only geographical but also social differences between the poleis?

Yes, and those differences determined how the state worked, what role citizens had, and how young people were educated.

So the development of city-states was also about how each community organized itself?

Yes, and that is a great starting point for further learning, because from here it becomes easy to compare Sparta, Athens, and the other Greek models.