Yazdegerd I

Yazdegerd I (Middle Persian: 𐭩𐭦𐭣𐭪𐭥𐭲𐭩 <yzdkrt^|> Yazdekerd, meaning "made by God"; New Persian: یزدگرد Yazdegerd) was the fourteenth Sasanian king of Persia and ruled from 399 to 420. He was the son of Shapur III (383–388). He succeeded to the Sasanian throne on the assassination of his brother Bahram IV in 399 and ruled for twenty-one years till his death in 420.

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. He is known in Sasanian sources (and also in Islamic Persian sources who use Sasanian sources as their references) as the sinner. However, this is propaganda made by the Zoroastrians due to his persecution of the Zoroastrians who opposed him, and his tolerance towards his non-Zoroastrian subjects, such as the Christians and the Jews. Yazdegerd also used the title of "Ramshahr" ("who maintains peace in his dominion"), which fitted to him, due to his peace with the Romans and tolerance towards his subjects. The title "Ramshahr" was a title used by the legendary Kayanid kings, and thus starts the Sasanian interest in Kayanid history, where they later would adopt the title of "Kay" and use the slogan "xwarrah".