Final answer:
The central interest of Sparta was the establishment and maintenance of a powerful, militaristic state dominated by an elite warrior class. They were concerned with military superiority, political power, and control over the subjugated helot population. Sparta formed the Peloponnesian League to maintain regional dominance and later engaged in the Peloponnesian War with Athens, which led to a brief Spartan hegemony before its decline.
Step-by-step explanation:
The central interest of the city-state of Sparta was maintaining a powerful military state focused on discipline, control, and dominance. As an oligarchy, Sparta was characterized by a ruling class of elite warriors. The Spartan society was primarily concerned with the training and maintenance of its soldiers, which was essential due to the vast majority of their population being helots — a class of serfs that were subjugated and required strict control to prevent rebellion.
The Spartans also sought power and influence in the region, forming the Peloponnesian League where they maintained dominance without exacting tribute, instead expecting allegiance in foreign policy. Their militaristic focus was a contrast to Athens, known for its art, culture, and democracy, leading to rivalry and eventual open conflict in the Peloponnesian War.
Sparta's power grew through conquest and wealth from agricultural land, yet they feared the growing influence of Athens, leading to sporadic conflicts and ultimately the Peloponnesian War, where Sparta eventually won but struggled to maintain its power and influence in the following years.
During this period, they also intervened in the affairs of other city-states, often affecting their political systems either through supporting oligarchies or overthrowing governments. However, when Thebes defeated Sparta in 371 BCE, Sparta's ability to sustain its military system weakened, leading to the collapse of the Peloponnesian League and Sparta's reduction in power.