Gaumata (Old Persian: ) or False Smerdis (Bardiya) was a magus in the Achaemenid era. According to the Behistun document, when Cambyses was fighting in Egypt he impersonated Cambyses's brother Bardiya. He reigned for about one year (522 to 521 BCE) as Smerdis in Persia. Gaumata led the oldest Persian uprising, which is known as the Gaumata movement.
According to the Behistun Inscription, the Magian imposter arrogated the Achaemenid throne by professing to be Bardiya (Smerdis), the son of Cyrus the Great. No case has been more plentifully recorded or more bitterly discussed in the plentiful history of the Achaemenids than the transfer of government from Cambyses II to Darius I. After his accession to the throne, Darius I had the official version engraved on the rock of Behistun in three languages (Elamite, Old Persian, and Babylonian) and distributed in all the languages of the empire (a fractional Aramaic counterpart has been discovered in the back of a papyrus from the Egyptian island of Elephantine (Darius II era).
As maintained by Darius I, Cambyses had his half-brother Bardiya assassinated, after a dream in which he saw Bardiya on his throne, but kept the killing a secret. When Cambyses shipped out on his Egyptian military expedition (525), a revolt developed in Persia, Media, and other territories, and a man referred to in the writings as a Magian named Gaumata plotted a coup d’état in Persia, claiming to Bardiya, as he resembled him. He was helped by his brother, the Magi Patizeithes. However, a Persian nobleman, Otanes, suspected that the Magian was an imposter and told his daughter Phaidime, who was married to Smerdis. According to Herodotus, Gaumata had had his ears cut off by Cyrus, so Otanes told his daughter to feel for the King's ears as they slept together. When she told him that the King had no ears, Otanes realised that he was an imposter. With six others he slew the King and Patizeithes. Darius then became King.
- Heidemarie Koch: Es kündet Dareios der König... (Kulturgeschichte der antiken Welt; 55). Verlag von Zabern, Mainz 2000, ISBN 3-8053-1934-7 (Nachdr. d. Ausg. Mainz 1992).
- Josef Wiesehöfer: Der Aufstand Gaumātas und die Anfänge Dareios' I. Habelt Verlag, Bonn 1978, ISBN 3-7749-1477-X (zugl. Dissertation, Frankfurt/M. 1977).
- Richard N. Frye: The History of ancient Iran. In: Handbuch der Altertumswissenschaft (3. Abt., T. 7), München 1984.
- Heidemarie Koch: Es kündet Dareios der König.... Philipp von Zabern, Mainz 1992 ISBN 3-8053-1347-0
- Walther Hinz: Darius und die Perser. Band 1. Holle, Baden-Baden 1976 ISBN 3-87355-165-9