information:extraction
First Golden Era (309–379)

Following Hormizd II's death, northern Arabs started to ravage and plunder the western cities of the empire, even attacking the province of Fars, the birthplace of the Sassanid kings. Meanwhile, Persian nobles killed Hormizd II's eldest son, blinded the second, and imprisoned the third (who later escaped into Roman territory). The throne was reserved for Shapur II, the unborn child of one of Hormizd II's wives who was crowned in utero: the crown was placed upon his mother's stomach. During his youth the empire was controlled by his mother and the nobles. Upon coming of age, Shapur II assumed power and quickly proved to be an active and effective ruler.

He first led his small but disciplined army south against the Arabs, whom he defeated, securing the southern areas of the empire. He then began his first campaign against the Romans in the west, where Persian forces won a series of battles but were unable to make territorial gains due to the failure of repeated sieges of the key frontier city of Nisibis, and Roman success in retaking the cities of Singara and Amida after they had previously fallen to the Persians.

These campaigns were halted by nomadic raids along the eastern borders of the empire, which threatened Transoxiana, a strategically critical area for control of the Silk Road. Shapur therefore marched east toward Transoxiana to meet the eastern nomads, leaving his local commanders to mount nuisance raids on the Romans. He crushed the Central Asian tribes, and annexed the area as a new province.

In the east around 325, Shapur II regained the upper hand against the Kushano-Sasanian Kingdom and took control of large territories in areas now known as Afghanistan and Pakistan. Cultural expansion followed this victory, and Sasanian art penetrated Transoxiana, reaching as far as China. Shapur, along with the nomad King Grumbates, started his second campaign against the Romans in 359 and soon succeeded in retaking Singara and Amida. In response the Roman emperor Julian struck deep into Persian territory and defeated Shapur's forces at Ctesiphon. He failed to take the capital, however, and was killed while trying to retreat to Roman territory. His successor Jovian, trapped on the east bank of the Tigris, had to hand over all the provinces the Persians had ceded to Rome in 298, as well as Nisibis and Singara, to secure safe passage for his army out of Persia.

From around 370, however, towards the end of the reign of Shapur II, the Sasanians lost the control of Bactria to invaders from the north: first the Kidarites, then the Hephthalites and finally the Alchon Huns, who would follow up with an invasion of India. These invaders initially issued coins based on Sasanian designs. Various coins minted in Bactria and based on Sasanian designs are extant, often with busts imitating Sassanian kings Shapur II (r. 309 to 379) and Shapur III (r. 383 to 388), adding the Alchon Tamgha and the name "Alchono" in Bactrian script on the obverse, and with attendants to a fire altar on the reverse.

Shapur II pursued a harsh religious policy. Under his reign, the collection of the Avesta, the sacred texts of Zoroastrianism, was completed, heresy and apostasy were punished, and Christians were persecuted. The latter was a reaction against the Christianization of the Roman Empire by Constantine the Great. Shapur II, like Shapur I, was amicable towards Jews, who lived in relative freedom and gained many advantages during his reign. At the time of his death, the Persian Empire was stronger than ever, with its enemies to the east pacified and Armenia under Persian control.