It is said that Shapur II (309–379) may have been the only king in history to be crowned in utero: the crown was placed upon his mother's belly. This child, named Shapur, was therefore born king. During his youth the empire was controlled by his mother and the nobles. Upon Shapur II's coming of age, he assumed power and quickly proved to be an active and effective ruler.
Shapur II first led his small but disciplined army south against the Arabs, whom he defeated, securing the southern areas of the empire.[13] He then started his first campaign against Romans in the west, experiencing early success. After the Siege of Singara, however, his conquests were halted by nomadic raids along the eastern borders of the empire. These raids threatened Transoxiana, a strategically critical area for control of the Silk Road. In addition, Shapur II's military forces were not sufficient to hold the territory he had taken in the west. He therefore signed a peace treaty with Constantius II (353–361) in which both sides agreed not to attack each other's territory for a limited period of time.
Shapur II then marched east toward Transoxiana to meet the eastern nomads. He crushed the Central Asian tribes, and annexed the area as a new province. He completed the conquest of the area now known as Afghanistan. Cultural expansion followed this victory, and Sassanid art penetrated Turkistan, reaching as far as China. Shapur II, along with the nomad King Grumbates, started his second campaign against the Romans in 359, this time with his full military force and support from the nomads. The campaign was overwhelmingly successful; a total of five Roman provinces were ceded to the Persians after its completion.
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 (324–337). Shapur II, like Shapur I, was amicable towards Jews, who lived in relative freedom and gained many advantages in his period (see also Raba (Talmud)).
At the time of Shapur's death, the Persian Empire was stronger than ever, with its enemies to the east pacified and Armenia under Persian control.
