Theodosius II was Emperor of the Roman Empire from 401 – 450 AD, the longest reign in the history of the Roman Empire. He was heavily influenced by his eldest sister, Pulcheria, throughout his reign and many of her views became official policy. On the death of his father Arcadius, Emperor of the Eastern Empire, in 408, he became Emperor at the age of 7. When, in June 421, Theodosius married the poet Aelia Eudocia, he had been Emperor for 13 years and was only 20 years of age.
In 429 Theodosius appointed a commission to collect all of the laws since the reign of Constantine, the first Christian Emperor, and create a fully formalized system of law. The plan was left unfinished by the original commission, but the work of the second commission was completed. Their collection was published in 438 as the Codex Theodosianus. The law code provided the basis for the law code of Justinian in the following century, which, in turn, became the foundation for much of the law of modern time. Theodosius was also responsible for the creation of Constantinople University.
It is interesting to note that although his reign was the longest and much was accomplished, Theodosius left the actual running of the Empire to others. He died in 450 as the result of a riding accident.