Year 406 BC was a year of the pre-Julian Roman calendar.
|Millennium:||1st millennium BC|
|Centuries:||6th century BC – 5th century BC – 4th century BC|
|Decades:||430s BC 420s BC 410s BC – 400s BC – 390s BC 380s BC 370s BC|
|Years:||409 BC 408 BC 407 BC – 406 BC – 405 BC 404 BC 403 BC|
|406 BC by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Gregorian calendar||406 BC|
|Ab urbe condita||348|
|Ancient Egypt era||XXVII dynasty, 120|
|- Pharaoh||Darius II of Persia, 18|
|Ancient Greek era||93rd Olympiad, year 3|
|Balinese saka calendar||N/A|
|Chinese calendar||甲戌年 (Wood Dog)|
2291 or 2231
— to —
乙亥年 (Wood Pig)
2292 or 2232
|Coptic calendar||−689 – −688|
|Ethiopian calendar||−413 – −412|
|- Vikram Samvat||−349 – −348|
|- Shaka Samvat||N/A|
|- Kali Yuga||2695–2696|
|Iranian calendar||1027 BP – 1026 BP|
|Islamic calendar||1059 BH – 1058 BH|
|Minguo calendar||2317 before ROC|
|Thai solar calendar||137–138|
−279 or −660 or −1432
— to —
−278 or −659 or −1431
|Wikimedia Commons has media related to 406 BC.|
- Callicratidas becomes the navarch of the Spartan fleet, replacing Lysander.
- Athens wins the Battle of Arginusae.
- Returning to Athens after the battle, Theramenes leads Athenian anger against the eight generals who were in the battle. They did not get survivors from the broken ships after the battle. The Athenian generals are put to death.
- Sparta asks for peace. Cleophon says no.
- The Carthaginians again invade Sicily and attack Agrigentum. Plague breaks out in their camp and Hannibal Mago dies.