Yazdegerd I, also spelled Yazdgerd I and Yazdgird I, was the Sasanian King of Kings 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. Yazdegerd I's largely-uneventful reign 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 recent predecessors. He enjoyed cordial relations with the Eastern Roman Empire and was entrusted by Arcadius with the guardianship of the latter's son Theodosius. Yazdegerd I is known for his friendly relations with the Jews and Christians of the Church of the East, which he acknowledged in 410. Because of this, he was praised by Jews and Christians as the new Cyrus the Great (r. 550 – 530 BC, king of the Iranian Achaemenid Empire who liberated the Jews from captivity in Babylon).