ACHÆMENIDÆ, ak′ē-men′i-dē, the Greek name of the Persian dynasty (558–330 b.c.) founded by Cyrus the Great, including Cambyses, Darius I and II, Xerxes, Artaxerxes, etc., and ended by Alexander the Great. The family took its name from an ancestor of Cyrus, found in Persian inscriptions as Haxamanisya, which the Greeks softened to Achæmenes (a-kē′men-ēz).