Yazdegerd I

Yazdegerd I (also spelled Yazdgerd and Yazdgird; Middle Persian: 𐭩𐭦𐭣𐭪𐭥𐭲𐭩) was the Sasanian King of Kings (shahanshah) of Iran from 399 to 420. A son of Shapur III (r. 383–388), he succeeded his brother Bahram IV (r. 388–399) after the latter's assassination.

The largely uneventful reign of Yazdegerd I is seen in Sasanian history as a period of renewal, although he was periodically known as "the Sinner" in native sources, Yazdegerd was more competent than his immediate predecessors. He enjoyed cordial relations with the Eastern Roman Empire and was entrusted by Arcadius with the guardianship of his son Theodosius. Yazdegerd I is known for his friendly relations with the Jews as well as the Christians of the Church of the East, which he acknowledged in 410. As a result, he was compared by the Jews and Christians to Cyrus the Great, the Achaemenid emperor who liberated the Jews from captivity in Babylon.

His religious policies were disliked by the nobility and the Zoroastrian clergy, whose power and influence he strove to curb. These efforts eventually backfired and Yazdegerd I met his end at the hands of the nobility in the remote northeast. The nobles then sought to prevent Yazdegerd's sons from ascending the throne; his eldest son, Shapur IV, was quickly killed after his accession and replaced with Khosrow. Another son, Bahram V, hurried to the Sasanian capital of Ctesiphon with an Arab army and pressured the nobility to acknowledge him as shah.