Achaemenid Dynasty, that is, during the time that this dynasty was in power in Iran (550 - 330  B.C.). http://en.wikipedia.org/wiki/Achaemenid_Empire . The Achaemenid Empire ( Persian : امپراتوری هخامنشی ) (c. 550–330 B.C.E.), pronounced /əˈkiːmənɨd/ ,     also known as the Persian Empire , was the successor state of the Median Empire