Yazdegerd I

Yazdegerd I, or Izdekerti ("made by God", Persian:یزدگرد یکم ), was the thirteenth Sassanid king of Persia and ruled from 399 to 421. He is believed by some to be the son of Shapur III (383–388) and by others to be son of Bahram IV (388–389). He succeeded to the Persian throne on the assassination of Bahram IV in 399 and ruled for twenty-one years till his death in 421.

Yazdegerd I's reign was largely uneventful. The king is described as being of a peaceful disposition. There were cordial relations between Persia and the Eastern Roman Empire as well as between Persia and the Western Roman Empire. Early during his reign, Yazdegerd was entrusted the care of the Roman prince Theodosius by his father Arcadius on the latter's death in 408, and Yazdegerd faithfully defended the life, power and possessions of the Roman prince.

Yazdegerd promoted Christianity in the early years of his reign and later opposed it. His alternate persecution of Zoroastrians and later Christians earned him the epithets of Al Khasha or "the Harsh" and Al Athim or "the Wicked" and Yazdegerd the Sinner. However, his general disposition towards the citizens of the Persian Empire was good. They gave him the epithet of Ramashtras or "the most quiet".

The later part of his reign was occupied by his attempts to convert Armenia to Zoroastrianism. During his last days, there took place a civil war between his sons. Bahram V emerged victorious and claimed the throne. Yazdegerd I died in 421 and was succeeded by his son Bahram V or Bahramgur.