Yazdegerd has tried to emancipate himself from the dominion of the magnates and of the Magi (a priestly caste serving a number of religions); thus, Christian and Zoroastrian sources view his reign differently.
Because he had stopped the persecution of the Christians, the Christian writers praise his clemency, but the sources dependent on Zoroastrian tradition refer to him as “Yazdegerd the Sinner.” He has also tried to limit the power of the nobles, but had finally answered their resistance with severity.
He has lived in peace and friendship with the Roman Empire and is therefore praised by Greek authors.
He appears to have been murdered in Khorasan, after which the nobles refuse to admit any of his sons to the throne.
However, one of them, Bahram, has the support of al-Mundhir, Lakhmid Arab king of Al-Hirah in Mesene (east of the lower Euphrates) and a Sassanian vassal, and also, apparently, of Mihr-Narseh, chief minister in Yazdegerd's last years, who is retained in office.
After Yazdegerd's death in 421, Persian nobles try to reclaim Bahram from Mundhir, so Mundhir sends his son Nu'man ahead with a brigade, then personally escorts Bahram with another brigade of 20,000 soldiers to Ctesiphon, where the nobles, after some negotiations, acknowledge Bahram as their ruler.
Bahram V, known as Gor (“the wild ass,” for his prowess in hunting the onager, reverses his father‘s policy of religious toleration, and revives the violent persecution of Christians in the Persian empire.
