Seven Achaemenid clans or seven Achaemenid houses were seven significant families that had key roles during the Achaemenid era.
[1] According to Herodotus, after the departure of Cambyses II for Egypt, the usurper Gaumata impersonated Bardiya (Smerdis), the younger brother of Cambyses, and became king.
A group of seven Persian noblemen became suspicious of the false king and conspired to overthrow Gaumata.
After the death of Gaumata, in a negotiation to determine the form of government, Otanes (Hutan) recommended a democratic government but his offer was not adopted and monarchy continued in Iran.
[2] The names of them were mentioned in Herodotus' Histories and the Behistun Inscription: Arthur Emanuel Christensen, a Danish historian and Iranologist, contends that Herodotus was mistaken to say that the prominence of these nobles and their successors was due to participation in murder of Gaumata; he further states that the institution of the "Seven Noble Clans" continued as late as the Parthian Empire.