Administrative divisions of the Sasanian Empire

According to the inscription, Eran was made up of the following provinces (shahr in Middle Persian):[1] ...Pars, Partaw (Pahlaw), Huzistan, Meshan, Asurestan, Nodshiragan (Adiabene), Arabestan, Adurbadagan (Azerbaijan), Armen (Armenia), Wirzan (Iberia), Sagan, Ardan (Albania), Balasagan up to the Kaf (Caucasus) Mountains and to the Alanan Gate and all of the Parishkhwar (Alborz) mountains, Mah (Media), Gurgan, Marγ, Harew, Abarshahr, Kirman, Sagestan (Sistan), Turestan, Makuran, Paradan, Hindestan, (India), Kushanshahr up to Pashkabur (Peshawar) and Kash, Suγd, Chach (Tashkent), and the lands of Mazun (Oman) on the other side of the sea.A similar list is mentioned in the Ka'ba-ye Zartosht of the 3rd-century Zoroastrian priest Kartir.

These divisions were not always used all over the realm, and records of other units are known, such as an awestam, which was ostensibly akin to a shahr and was administered by an awestamdar.

[2] During the reforms of Kavad I (r. 488–496, 498–531) and his son and successor Khosrow I (r. 531–579),[3][4] the provinces were grouped into four frontier regions (kusts), with a marshal (spahbed) in charge of each district; a chancery was also added to keep the soldiers equipped.

[5][6][7] Before Kavad and Khosrow's reforms, the Iranians' general (Eran-spahbed) managed the empire's army.

[9][5] According to modern historian Negin Miri, the list of Sasanian administrators and their level of authority presented in a hierarchical model was the following:[10]