Achaeans, a kee'anz, one of the four main divisions of the ancient Greeks. They migrated from Thessaly to the Peloponnesus, which they ruled in the heroic period. From very early times a confederacy existed among the twelve towns of this region. After the death of Alexander the Great it was broken up, but was revived again in 280 B. C., and from this time grew in power till it spread over the whole Peloponnesus. It was finally dissolved by the Romans in 146 B. C., and after this the whole of Greece, except Thessaly, was called Achaia or Achaea. See GREECE.