Conflicting accounts shroud the details of the fall of the Parthian Empire and subsequent rise of the Sasanian Empire in mystery. The Sassanid Empire was established in Estakhr by Ardashir I.
Papak was originally the ruler of a region called Khir. However, by the year 200, he managed to overthrow Gochihr, and appoint himself as the new ruler of the Bazrangids. His mother, Rodhagh, was the daughter of the provincial governor of Pars. Papak and his eldest son Shapur managed to expand their power over all of Pars. The subsequent events are unclear, due to the elusive nature of the sources. It is certain, however, that following the death of Papak, Ardashir, who at the time was the governor of Darabgerd, got involved in a power struggle of his own with his elder brother Shapur. Sources reveal that Shapur, leaving for a meeting with his brother, was killed when the roof of a building collapsed on him. By the year 208, over the protests of his other brothers who were put to death, Ardashir declared himself ruler of Pars.
Once Ardashir was appointed shahanshah, he moved his capital further to the south of Pars and founded Ardashir-Khwarrah (formerly Gur, modern day Firuzabad). The city, well supported by high mountains and easily defendable through narrow passes, became the center of Ardashir’s efforts to gain more power. The city was surrounded by a high, circular wall, probably copied from that of Darabgird, and on the north-side included a large palace, remains of which still survive today. After establishing his rule over Pars, Ardashir I rapidly extended his territory, demanding fealty from the local princes of Fars, and gaining control over the neighboring provinces of Kerman, Isfahan, Susiana and Mesene. This expansion quickly came to the attention of Artabanus V, the Parthian king, who initially ordered the governor of Khuzestan to wage war against Ardashir in 224, but the battles were victories for Ardashir. In a second attempt to destroy Ardashir, Artabanus V himself met Ardashir in battle at Hormozgan, where Artabanus V met his death. Following the death of the Parthian ruler, Ardashir I went on to invade the western provinces of the now defunct Parthian Empire.
Rock-face relief at Naqsh-e Rustam of Persian emperor Shapur I (on horseback) capturing Roman emperor Valerian (standing) and Philip the Arab (kneeling), suing for peace, following the victory at Edessa.
At that time the Arsacid dynasty was divided between supporters of Artabanus V and Vologases VI, which probably allowed Ardashir to consolidate his authority in the south with little or no interference from the Parthians. Ardashir was aided by the geography of the province of Fars, which was separated from the rest of Iran. Crowned in 224 at Ctesiphon as the sole ruler of Persia, Ardashir took the title shahanshah, or “King of Kings” (the inscriptions mention Adhur-Anahid as his Banbishnan banbishn, “Queen of Queens”, but her relationship with Ardashir is not established), bringing the 400-year-old Parthian Empire to an end, and beginning four centuries of Sassanid rule.
In the next few years, local rebellions would form around the empire. Nonetheless, Ardashir I further expanded his new empire to the east and northwest, conquering the provinces of Sistan, Gorgan, Khorasan, Margiana (in modern Turkmenistan), Balkh and Chorasmia. He also added Bahrain and Mosul to Sassanid’s possessions. Later Sassanid inscriptions also claim the submission of the Kings of Kushan, Turan and Mekran to Ardashir, although based on numismatic evidence, it is more likely that these actually submitted to Ardashir’s son, the future Shapur I. In the west, assaults against Hatra, Armenia and Adiabene met with less success. In 230, he raided deep into Roman territory, and a Roman counter-offensive two years later ended inconclusively, although the Roman emperor, Alexander Severus, celebrated a triumph in Rome.
The Humiliation of Valerian by Shapur (Hans Holbein the Younger, 1521, pen and black ink on a chalk sketch, Kunstmuseum Basel)
Ardashir I’s son Shapur I continued the expansion of the empire, conquering Bactria and the western portion of the Kushan Empire, while leading several campaigns against Rome. Invading Roman Mesopotamia, Shapur I captured Carrhae and Nisibis, but in 243 the Roman general Timesitheus defeated the Persians at Rhesaina and regained the lost territories. The emperor Gordian III’s (238–244) subsequent advance down the Euphrates was defeated at Meshike (244), leading to Gordian’s murder by his own troops and enabling Shapur to conclude a highly advantageous peace treaty with the new emperor Philip the Arab, by which he secured the immediate payment of 500,000 denarii and further annual payments.
Shapur soon resumed the war, defeated the Romans at Barbalissos (253), and then probably took and plundered Antioch. Roman counter-attacks under the emperor Valerian ended in disaster when the Roman army was defeated and besieged at Edessa and Valerian was captured by Shapur, remaining his prisoner for the rest of his life. Shapur celebrated his victory by carving the impressive rock reliefs in Naqsh-e Rostam and Bishapur, as well as a monumental inscription in Persian and Greek in the vicinity of Persepolis. He exploited his success by advancing into Anatolia (260), but withdrew in disarray after defeats at the hands of the Romans and their Palmyrene ally Odaenathus, suffering the capture of his harem and the loss of all the Roman territories he had occupied.
The spread of Manichaeism (300– 500)
Shapur had intensive development plans. He ordered the construction of the first dam bridge in Iran and founded many cities, some settled in part by emigrants from the Roman territories, including Christians who could exercise their faith freely under Sassanid rule. Two cities, Bishapur and Nishapur, are named after him. He particularly favored Manichaeism, protected Mani (who dedicated one of his books, the Shabuhragan, to him) and sent many Manichaean missionaries abroad. He also befriended a Babylonian rabbi called Samuel.
This friendship was advantageous for the Jewish community and gave them a respite from the oppressive laws enacted against them. Later kings reversed Shapur’s policy of religious tolerance. Under pressure from Zoroastrian Magi and influenced by the high-priest Kartir, Bahram I killed Mani and persecuted his followers. Bahram II was, like his father, amenable to the wishes of the Zoroastrian priesthood. During his reign, the Sassanid capital Ctesiphon was sacked by the Romans under Emperor Carus, and most of Armenia, after half a century of Persian rule, was ceded to Diocletian.
Succeeding Bahram III (who ruled briefly in 293), Narseh embarked on another war with the Romans. After an early success against the Emperor Galerius near Callinicum on the Euphrates in 296, Narseh was decisively defeated. Galerius had been reinforced, probably in the spring of 298, by a new contingent collected from the empire’s Danubian holdings. Narseh did not advance from Armenia and Mesopotamia, leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via Armenia. Narseh retreated to Armenia to fight Galerius’ force, to Narseh’s disadvantage: the rugged Armenian terrain was favorable to Roman infantry, but not to Sassanid cavalry. Local aid gave Galerius the advantage of surprise over the Persian forces, and, in two successive battles, Galerius secured victories over Narseh.
Rome and vassal Armenia around 300, after Narseh’s defeat
During the second encounter, Roman forces seized Narseh’s camp, his treasury, his harem, and his wife. Galerius advanced into Media and Adiabene, winning successive victories, most prominently near Erzurum, and securing Nisibis (Nusaybin, Turkey) before October 1, 298. He moved down the Tigris, taking Ctesiphon. Narseh had previously sent an ambassador to Galerius to plead for the return of his wives and children. Peace negotiations began in the spring of 299, with both Diocletian and Galerius presiding.
The conditions of the peace were heavy: Persia would give up territory to Rome, making the Tigris the boundary between the two empires. Further terms specified that Armenia was returned to Roman domination, with the fort of Ziatha as its border; Caucasian Iberia would pay allegiance to Rome under a Roman appointee; Nisibis, now under Roman rule, would become the sole conduit for trade between Persia and Rome; and Rome would exercise control over the five satrapies between the Tigris and Armenia: Ingilene, Sophanene (Sophene), Arzanene (Aghdznik), Corduene, and Zabdicene (near modern Hakkâri, Turkey).
The Sassanids ceded five provinces west of the Tigris, and agreed not to interfere in the affairs of Armenia and Georgia. In the aftermath of this defeat, Narseh gave up the throne and died a year later, leaving the Sassanid throne to his son, Hormizd II. Unrest spread throughout the land, and while Hormizd II suppressed revolts in Sakastan and Kushan, he was unable to control the nobles and was subsequently killed by Bedouins in a hunting trip in 309.