The empire was divided into satrapies, whose number varied from twenty to twenty-eight at different periods of Darius’ reign.[3] Persia proper was alone excluded, receiving special treatment as the home of the ruling race. The civil and military powers in these satrapies or provinces were divided. Three independent officials, with separate departments of administration, were appointed to each. In the case of important provinces the satraps were generally drawn from great families connected with the Achæmenids; but in the case of the others the field of choice seems to have been practically unlimited, and governors were selected from among the comparatively poor as well as from the wealthy, from the subject races as well as from the Persians. The instances in which persons not of Persian or Medic extraction were appointed to these important posts seem, however, to have been rare and exceptional. There was no set period for the tenure of the office. The duration of the governor’s administration depended on the pleasure of the Great King. In all civil matters the governor had absolute authority. He controlled the administration of the taxes and the dispensation of justice; he possessed the power of life and death. As viceroy, representing the king, he was allowed to maintain a court and bodyguard, with other minor attributes of regal power. Under ordinary circumstances he neither commanded nor even controlled the military forces in his province; in fact, a common policy of the central government seems to have been to place a personal enemy of the governor in command of the troops, whose relations with the king were, of course, direct. It may be that under exceptional circumstances,—as, for instance, when Artaphernes was satrap of Sardes at the time of the Ionian revolt,—the supreme direction of military operations was entrusted to a governor of peculiarly high distinction. The secretary of state within the province was a third official who had immediate relations to the king. Though nominally the chief assistant of the governor, he was in reality appointed to watch his conduct, and to report irregularities or suspicious circumstances to the central government at Susa.