Ruled between 408-450 AD, Theodosius II was the son and successor of Arcadius. He preferred the study of theology and astronomy to public affairs leaving it to his sister Pulcheria and his wife Eudocia.
The most important political events of his reign were the establishment of Valentinian III as emperor in the West in 425 and the raids into the Byzantine Empire by the Huns under Attila. In 431, Theodosius summoned the Council of Ephesus, which condemned Nestorianism, and in 449 he convoked and upheld the Robber Synod, which declared the orthodoxy of Eutychianism. He also founded the University of Constantinople (today's Istanbul) in 425, declared the Theodosian Code (Codex Theodosianus) in 438, and restored the City Walls.
Marcian, His brother-in-law, succeeded him when he died in 450 AD by a riding accident.