 king of kings, indeed translated in Greek as "basileus tōn basileōn", later adopted by the Byzantine emperors) of Persia under the Achaemenid dynasty whose vast empire in Asia lasted for 200 years up to the year 330 BC, and later adopted by successors of the Achaemenid Empire whose monarchial names were also succeeded by "the great".In comparison, "high king" was used by ancient rulers in Great Britain and Ireland, as well as Greece.In the 2nd millennium BCE Near East, there was a tradition of reciprocally using such addresses between powers, as a way of diplomatically recognizing each other as an equal.