Achaea () or Achaia (; Greek: Ἀχαΐα, Akhaḯa, Ancient Greek: [akʰaía]) is the northernmost region of the Peloponnese, occupying the coastal strip north of Arcadia. Its approximate boundaries are: to the south, Mount Erymanthus; to the south-east, Mount Cyllene; to the east, Sicyon; and to the west, the Larissos river. Apart from the plain around Dyme in the west, Achaea is generally a mountainous region.