A confederacy of Achaean and other Peloponnesian states in ancient Greece. Its name derived from the region of Achaea in the northern Peloponnese. In the 4th century bc an alliance was forged that was dissolved in 338 bc. The League was refounded in 280 bc, under the leadership of Aratus of Sicyon. It became involved in wars with Macedonia and Sparta, before allying itself with Rome in 198. However, war with Rome in 146 led to defeat and the dissolution of the League.