and
Shapur I near
Salmas Since the area of Adurbadagan had been ruled by local dynasties, initially by Atropates and his descendants, and a branch of the Parthian
Arsacids from the 1st-century AD. During the late Parthian era, the empire was declining, resulting in the weakening of hold over western Iran. The
Iranologist Touraj Daryaee argues that the reign of the Parthian monarch
Vologases V () was "the turning point in Arsacid history, in that the dynasty lost much of its prestige." The people of Adurbadagan (both nobility and peasantry) allied themselves with the Persian
Sasanian prince
Ardashir I () during his wars against Vologases V's son and second successor
Artabanus IV (). In 226, Adurbadagan submitted with little resistance to Ardashir I after he had defeated and killed Artabanus IV at the
Battle of Hormozdgan. Ardashir I and his son and heir
Shapur I () are depicted in a
rock relief near
Salmas, possibly a testimonial to the Sasanian conquest of Adurbadagan. The nobility of Adurbadagan most likely allied themselves the Sasanians due to a desire for a strong state capable of maintaining order. The priesthood, who may have felt alienated by the easy-going Arsacids, probably also supported the Sasanian family, due to its association with
Zoroastrianism. The events that occurred during the early Sasanian period increased the importance of Adurbadagan. While the Parthian Empire fell in Iran, their
collateral line in
Armenia prevented Ardashir I from conquering Armenia (or least all of it). Although Armenia was finally conquered by Shapur I in 252, the country would continue to prove problematic for the Sasanians, even more it converted to
Christianity. As a result, Adurbadagan had been since the advent of the Sasanians fortified into a military bastion, and then religious one. However, in 241/2, Shapur I had to mount an expedition in Adurbadagan to quell unrest. After that, the province seemingly became completely subdued. () Under
Kavad I () and his son and successor
Khosrow I () the empire was divided into four frontier regions (
kust in
Middle Persian), with a military commander (
spahbed) in charge of each district. The frontier regions were known as
xwarāsān (East),
xwarārān (West),
nēmrōz (South) and
abāxtar (North). Due to negative connotations, the term
abāxtar was substituted with the name of Adurbadagan. Due to sharing the same name, the
kust of Adurbadagan and its namesake province were often incorrectly seen as being the same in sources. The province of Adurbadagan, along with provinces such as
Gilan and
Caucasian Albania were part of the northern quarter. , where the fire of
Adur Gushnasp was stored. In August 591, the
Battle of Blarathon took place near Ganzak, between
Khosrow II's forces and the rebel forces of Bahram Chobin. However, not long after the battle, Khosrow II's maternal uncle
Vistahm rebelled (precise date unknown, 590/1–596 or 594/5–600), and managed to gain control of some parts of Adurbadagan. He was, however, defeated by Khosrow II and the Sasanian general
Smbat IV Bagratuni. During the
Byzantine–Sasanian War of 602–628, the fire temple of
Adur Gushnasp was sacked in 623/4 by the Byzantine emperor
Heraclius. The Iranians succeeded in saving the fire, which they later restored to the temple, which was quickly rebuilt. The apocalyptical Middle Persian text
Zand-i Wahman yasn may report some form of contemporary memory of the destruction of the temple; "They will remove Adur Gushnasp from its place . . . on account of (the devastation of) these armies, Adur Gushnasp will be carried to
Padishkhwargar." In 651, the
Arabs invaded Adurbadagan, which was the domain of the
Ispahbudhan brothers
Isfandyadh and Bahram. Isfandyadh made a stand against the Arabs, where a battle was fought. He was, however, defeated and captured by the Arabs. While Isfandyadh was in captivity, he told the Arab general
Bukayr ibn Abdallah, that if he sought to conquer Adurbadagan easily and peacefully, he should make peace with him. According to
Bal'ami, Isfandyadh is known to have said that: "If you [were to] kill me all of Adurbadagan [will] rise in avenging my blood, and will wage war against you." The Arab general accepted Isfandyadh's advice and made peace with him. However, Bahram, the brother of Isfandyadh, refused to submit to the Arab forces and kept resisting them. Although he was quickly defeated by the Arabs, and was forced to flee from Adurbadagan. Adurbadagan thus came under Arab suzerainty. == Religious importance ==