Who made up the peloponnesian league and why did its members resent Athens?

The Peloponnesian League was primarily made up of city-states in the Peloponnese, including Sparta, Corinth, and Megara, among others. Its members resented Athens due to its growing power and imperial ambitions, especially following the establishment of the Delian League, which Athens dominated. This resentment was fueled by Athens' aggressive expansion, heavy taxation on its allies, and perceived arrogance, leading to tensions that ultimately sparked the Peloponnesian War.