Achaea or Achaia, sometimes transliterated from Greek as Akhaia, is one of the regional units of Greece. It is part of the region of Western Greece and is situated in the northwestern part of the Peloponnese peninsula. The capital is Patras which is the third largest city in Greece.

The Peloponnese, Peloponnesus or Morea is a peninsula and geographic region in Southern Greece, and the southernmost region of the Balkans. It is connected to the central part of the country by the Isthmus of Corinth land bridge which separates the Gulf of Corinth from the Saronic Gulf. From the late Middle Ages until the 19th century, the peninsula was known as the Morea, a name still in colloquial use in its demotic form.