Traditional view
The traditional view is based on several ancient sources, including the Behistun inscription as well as Herodotus, in Ctesias, and Justin, although there are minor differences among them. The three oldest surviving sources agree that Gaumata/Pseudo-Smerdis/Sphendadates was overthrown by Darius and others in a coup d'état, and that Darius then ascended the throne. Most sources (including Darius himself, Herodotus and Ctesias) have Darius as part of a group of seven conspirators. In Greek and Latin sources, Darius subsequently gained kingship by cheating in a contest.
Bardiya was the younger son of Cyrus the Great and a full or half-brother of Cambyses II. According to Ctesias, on his deathbed Cyrus appointed Bardiya as satrap (governor) of some of the far-eastern provinces. According to Darius the Great, Cambyses II, after becoming king of Persia but before setting out for Egypt, killed Bardiya and kept this secret. However, according to Herodotus (who gives two detailed stories), Bardiya went to Egypt with Cambyses and was there for some time but later Cambyses sent him back to Susa out of envy, because "Bardiya alone could draw the bow brought from the Ethiopian king." Herodotus then states that "Cambyses had a dream in which he saw his brother sitting on the royal throne. As a result of this dream Cambyses sent his trusted counselor Prexaspes from Egypt to Susa with the order to kill Smerdis" (i.e., Bardiya).
Bardiya's death was not known to the people, and so in the spring of 522 BC, a usurper pretended to be him and proclaimed himself king on a mountain near the Persian town of Paishiyauvada. Darius claimed that the real name of the usurper was Gaumata, a Magian priest from Media; this name has been preserved by Justin but given to his brother (called Patizeithes by Herodotus), who is said to have been the real promoter of the intrigue. According to Herodotus, the name of the Magian usurper was Oropastes, but according to Ctesias it was Sphendadates.
The despotic rule of Cambyses, coupled with his long absence in Egypt, contributed to the fact that "the whole people, Persians, Medes and all the other nations," acknowledged the usurper, especially as he granted a tax relief for three years.
Cambyses began to march against him, but died in the spring of 522 BC in disputed circumstances. Before his death he confessed to the murder of his brother, and publicly explained the whole fraud, but this was not generally believed. Nobody had the courage to oppose the new king, who ruled for seven months over the whole empire. The new king transferred the seat of government to Media. A number of Persian nobles discovered that their new ruler was an impostor, and a group of seven nobles formed a plot to kill him. In September 522 BC they surprised him at a castle in Nisa (on the Nisaean plain) and stabbed him to death. One of the seven, Darius, was proclaimed as ruler shortly after.
While the primary sources do not agree on the names and many other details, the three oldest surviving sources (Darius himself, Herodotus and Ctesias) all portray Gaumata/Pseudo-Smerdis/Sphendadates as an imposter who usurped the throne by posing as one of the sons of Cyrus the Great, i.e. as one of the brothers of Cambyses II. In Darius' trilingual Behistun inscription, the prince being impersonated is named "Pirtiya" in Elamite, "Bardiya" in Old Persian, and "Barziya" in Akkadian. In Herodotus' Histories, the prince and his imposter have the same name (Smerdis). For Ctesias, Sphendadates poses as 'Tanyoxarces'. Other Greek sources have various other names for the figure being impersonated, including 'Tanoxares', 'Mergis' and 'Mardos'.
