A riot breaks out in Constantinople; the Great Palace is burned to the ground. Gainas, an ambitious Gothic leader, attempts to evacuate his soldiers out of the city, but 7,000 armed Goths are trapped and killed by order of Arcadius. After the massacre, Gainas tries to escape across the Hellespont, but his rag-tag ad hoc fleet is destroyed by Fravitta, a Gothic chieftain in imperial service.
Winter – Gainas leads the remaining Goths back to their homeland across the Danube. They meet the Huns and are defeated; the Hunnic chieftain Uldin sends the head of Gainas to Constantinople, where Arcadius receives it as a diplomatic gift.
The ChineseBuddhist monk Huiyuan, who founded the Pure Land Buddhism sect and the monastery on Mount Lushan, writes the book On Why Monks Do Not Bow Down Before Kings in this year. In his book he argues that although the Buddhist clergy should remain independent and undisturbed by politics, the Buddhist laymen nonetheless make good subjects under monarchs, due to their fear of retribution of karma and desire to be reborn in paradise.
King Radagaisus leads an invasion with a force of 20,000 men and crosses the Alps. He spends the winter in the Po Valley and is observed by Stilicho, who lacks sufficient strength to prepare an offensive against the invading German tribes. The exact numbers of the migration are unknown, probably nearly 100,000, including Alans, Burgundians, Goths, Vandals, and other smaller tribes.
End of Roman rule in Britain: After 360 years of occupation, the local regional British-Roman leaders raise their own levies for defence against Saxon sea rovers. They cultivate oysters, having learned the technique from the Romans.
Alaric also demands, and obtains, the freedom of 30,000 people who had been enslaved in Rome.
The Huns under Uldin cross the lower Danube and attack the Eastern Roman Empire, setting fire to frontier forts and taking control of the Castra Martis (modern Bulgaria). The Romans negotiate for peace, but Uldin demands an exorbitant gold tribute in return for his withdrawal. This demand is rejected and Anthemius forces the Huns back across the Danube.