Theodosius II was born in AD 401, the son of Arcadius and Aelia Eudoxia.
When in AD 408 Arcadius died his son succeeded to the throne without any violence.
With Theodosius II still an infant, the regency of Constantinople fell to the praetorian prefect Anthemius.
And after seeing Rome sacked by Alaric, Anthemius took to extensively fortifying Constantinople, in AD 413 building the great 'Wall of Theodosius' which protected a city which had long outgrown the original Wall of Constantine.
In AD 414 Anthemius handed over the regency to Theodosius II's sister Aelia Pulcheria who, only fifteen at the time, was proclaimed Augusta.
Pulcheria was a devout Christian, so much so that many saw her demands of chastity and asceticism as attempts to turn the court of Constantinople into a nunnery.
Then in AD 416 Theodosius II, at fifteen years of age, was declared ruler of Constantinople in his own right. However, Pulcheria continued to administer his government on his behalf for his entire reign.
The most notable event of the following years was the decision by the government of the eastern empire to establish Theodosius II's cousin Valentinian III as the western emperor in AD 425. Theodosius II even travelled toward Italy to crown his cousin himself, but fell ill on the way, having to let Helion, his chief minister, crown Valentinian III on his behalf.
The most outstanding feature of the reign of Theodosius II arrived in AD 438, when the Theodosian Code was published. It was a compilation of imperial edicts stretching back over a century, made up of sixteen books. It had been compiled over eight years and had been agreed with Valentinian III.
In the later years of Theodosius II's reign the Danubian provinces suffered enormously under invasions by the Huns.
For a brief period Pulcheria, who earlier had forced the emperor's wife Aelia Eudocia into exile to preserve her power, was eclipsed during the AD 440's by the eunuch Chrysaphius Zstommas. But his influence soon waned, leaving Pulcheria to return to the very head of Theodosius II's government.
Then, in the year AD 450, Theodosius II while riding near the river Lycus was thrown from his horse. He suffered a severe injury to his spine and died.