The term "Peloponnesian" refers to anything related to the Peloponnesus, a large peninsula in southern Greece. This region is known for its rich history and significant role in ancient Greek civilization. It is home to important city-states such as Sparta and Corinth, which were influential in military and political affairs. The most notable historical event associated with the Peloponnesian region is the Peloponnesian War, a conflict fought between the Delian League, led by Athens, and the Peloponnesian League, led by Sparta. This war, lasting from 431 to 404 BCE, significantly impacted Greek society and politics, leading to the eventual decline of Athenian power.