The main settlement area of the Parthians in the early antiquity was the province of
Parthava, but with the political and territorial changes during the
Arsacid and later the
Sasanian period, the demographic situation of ancient Iran changed drastically. Since the Arsacids and the successive conquest of western territories under
Mithridates I and
Mithridates II, as well as the shift of the main administration to the west, the settlement of Parthians in western Iran is attested. The expansion of the Parthian people and the Arsacid dynasty to Mesopotamia and the Caucasus required prior settlement of adjacent areas, particularly Media Atropatene and Media Magna. This westward migration of the Parthians was so strong that the history and provincial titles speak of a veritable westward shift of the province of Pahlaw/Parthava. Therefore, it is noteworthy that the history mentions two different provinces called Pahlaw/Parthava. • Classically attested eastern province
Parthava: This province existed since the Achaemenids and was bordered by Gorgan to the northwest, Khwarazm to the north, Sogdiana to the northeast, Balch to the east, Herat to the southeast, and Kerman to the south. Later Sasanian sources no longer mention a province called Parthava in the east, but instead speak of the province of Abarshahr, which means
city of the Aparni. Perhaps the original province of the Parthians had become a settlement area of the Aparni due to political events and the proximity to the Dahae-Scythian areas. However, the Arsacids themselves never lost their connection to their original province, as evidenced by the royal tombs in
Parthaunisa/Mithradatkert. • Pahla/Pahlaw in Late Antiquity and Post-Islamic Period: During the Sassanid era, the province of Parthia was newly located in central Iran as a neighboring province of Pars and Khuzistan. As is known, this region was considered the last bastion of the Arsacids. In Shapur's inscriptions, Parthia even shares second place in the list of provinces, indicating its importance for the empire. The Abnun inscriptions also attest to a further westward shift of Parthia, recounting Roman attacks against Pars and Parthia, although these were not directed against eastern Iran. or excluding Ray and Spahan, it encompassed Qumis, Tabaristan, Khorasan, Sistan, Kerman, Makran, Qazwin, Dailam, and Talaqan. Ghodrat-Dizaji summarizes the historical shift of the province as follows: The correspondence of Pahla with the Median provinces can be traced on the one hand to the identification of the governors of these regions with the Parthians. Thus, the regions and governors who were subject to or incorporated into the Parthian Arsacids called themselves subordinate to the Arsacid royal house and Parthians, which, in addition to the political component, also encompasses an identity-cultural component and thus also explains the Parthianization of western territories. On the other hand, the migration of the earlier Parthians to the region played a decisive role in the ethnogenesis of the middle and late Parthians, which is why, in addition to the political component, a strong ethnocultural component is identified by historians. In Pahla, the rule was not only limited to the Parthian Arsacid dynasty.
Moses of Chorene also includes the
Karen,
Suran, and
Aspahbat (Ispahbad) houses as sub-rulers of Pahla. According to Tabari, the Karenids had their seat in
Mah Nihavand, the
Aspahbad (Ispahbad) in Ray, and the
Surenids in
Sigistan, while the last Arsacid, Ardawan IV, ruled over the entire
Jibal (meaning Media). == References ==