Away in the East Cyrus had been succeeded in 529 B.C. by Cambyses, who had annexed Egypt and on whose death in 522 a Magian impostor, Gaumata, had seized the throne.
The real name of the usurper was, as Darius tells us, Gaumata, a Magian priest from Media; this name has been preserved by Justin i.
He gives a faithful sketch of the doctrines, mythology and dualistic system of the Magian Zoroaster.
But, whatever may have been his date, he was their teacher and instructor in the Magian religion, modified their former religious customs, and introduced a variegated and composite belief."
Darius, in fact, entered Babylon as a conqueror; after the murder of the Magian it had recovered its independence under Nidinta-Bel, who took the name of Nebuchadrezzar III., and reigned from October 521 B.C. to August 520 B.C., when the Persians took it by storm.