|Centuries:||2nd century – 3rd century – 4th century|
|Decades:||260s 270s 280s – 290s – 300s 310s 320s|
|Years:||287 288 289 – 290 – 291 292 293|
|290 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1043|
|Chinese calendar||己酉年 (Earth Rooster)
2986 or 2926
— to —
庚戌年 (Metal Dog)
2987 or 2927
|- Vikram Samvat||346–347|
|- Shaka Samvat||212–213|
|- Kali Yuga||3391–3392|
|Iranian calendar||332 BP – 331 BP|
|Islamic calendar||342 BH – 341 BH|
|Minguo calendar||1622 before ROC
|Seleucid era||601/602 AG|
|Thai solar calendar||832–833|
Year 290 (CCXC) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerius and Valerius (or, less frequently, year 1043 Ab urbe condita). The denomination 290 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.
- Emperors Diocletian and Maximian meet in Milan on the five-year anniversary of their rule to discuss politics and war. Rome becomes a ceremonial capital.
- Carausius, who has established himself as king of Britain, is also reluctantly acknowledged by Diocletian and Maximian as third emperor. He defeats during his reign Frankish and Saxon raids on the English coast.
- Carausius begins to build a series of fortifications on the Saxon Shore in south-east England.
- May 17 – Emperor Jin Wudi, founder of the Western Jin Dynasty, dies after a 25-year reign. He reunifies north and south, but gives away many dukedoms to his kinsmen. Crown Prince Jin Huidi succeeds his father and has to deal with conflicts among the aristocratic families in China.