|Centuries:||4th century – 5th century – 6th century|
|Decades:||370s 380s 390s – 400s – 410s 420s 430s|
|Years:||402 403 404 – 405 – 406 407 408|
|405 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1158|
|Chinese calendar||甲辰年 (Wood Dragon)
3101 or 3041
— to —
乙巳年 (Wood Snake)
3102 or 3042
|- Vikram Samvat||461–462|
|- Shaka Samvat||327–328|
|- Kali Yuga||3506–3507|
|Iranian calendar||217 BP – 216 BP|
|Islamic calendar||224 BH – 223 BH|
|Minguo calendar||1507 before ROC
|Seleucid era||716/717 AG|
|Thai solar calendar||947–948|
Year 405 (CDV) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Stilicho and Anthemius (or, less frequently, year 1158 Ab urbe condita). The denomination 405 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Emperor Honorius closes the Flavian Amphitheatre (Colosseum) in an austerity move that abolishes amusements.
- Stilicho, Roman general (magister militum), orders the Sibylline Books to be burned, according to the Roman poet Rutilius Claudius Namatianus.
- Stilicho crushes a coalition of Asding Vandals, Ostrogoths, and Quadi with an army raised from forces of the Rhine frontier, leaving this sector dangerously weakened.
- 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.
- Flavius Aetius is sent as a child hostage at the court of Alaric I, king of the Visigoths.
- The Khitan are first mentioned in Chinese chronicles. They wander along the boundaries of Kara-muren, and form part of the Donghu (Tong-hou) confederation.
Arts and Sciences
- The Armenian alphabet is devised by Mesrop Mashtots.
- The Japanese court officially adopts the Chinese writing system (approximate date).
- Theon of Alexandria, Greek mathematician, dies at age 70 (approximate), having been helped in his work by his daughter Hypatia.
- Jerome's Vulgate translation of the Bible into Latin is completed by his translations of the Tanakh from the Hebrew language.
- In the Roman province of Africa, Augustine of Hippo opposes Donatism as a heresy.
- Ricimer, de facto ruler of the Western Roman Empire (approximate date)
- Salvian, Christian writer (approximate date)
- Yuan Qigui, empress and wife of Wen of Liu Song (d. 440)
- November 11 – Arsacius of Tarsus, archbishop of Constantinople
- Moses the Black, Christian monk and priest (b. 330)
- Murong De, emperor of the Xianbei state Southern Yan (b. 336)
- Richu, emperor of Japan (approximate date)
- June 26 – Saint Vigilius, bishop of Trent (b. 353)
- Theon of Alexandria, last director of the Library of Alexandria (approximate date)