|Centuries:||2nd century – 3rd century – 4th century|
|Decades:||240s 250s 260s – 270s – 280s 290s 300s|
|Years:||267 268 269 – 270 – 271 272 273|
|270 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1023|
|Chinese calendar||己丑年 (Earth Ox)
2966 or 2906
— to —
庚寅年 (Metal Tiger)
2967 or 2907
|Coptic calendar||−14 – −13|
|- Vikram Samvat||326–327|
|- Shaka Samvat||192–193|
|- Kali Yuga||3371–3372|
|Iranian calendar||352 BP – 351 BP|
|Islamic calendar||363 BH – 362 BH|
|Minguo calendar||1642 before ROC
|Seleucid era||581/582 AG|
|Thai solar calendar||812–813|
Year 270 (CCLXX) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Antiochianus and Orfitus (or, less frequently, year 1023 Ab urbe condita). The denomination 270 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 Claudius II Gothicus dies of plague while preparing to fight the Vandals and Sarmatians, who have invaded Pannonia. He is succeeded by his brother Quintillus, who briefly holds power over the Roman Empire.
- Quintillus commits suicide and is succeeded by an associate of his brother Lucius Domitius Aurelianus, the military leader who distinguished himself last year at the Battle of Naissus (Serbia).
- Aurelianus pushes the Goths back across the Danube and recovers Roman territory.
- The Romans leave Utrecht after regular invasions of Germanic tribes.
- Crisis of the Third Century: An economic crisis strikes the Roman empire; due to the partition of the empire, invasions and usurpations and the sacking of the countryside and cities by invaders, agricultural and industrial production are significantly decreased, and mines lie unused. A monetary crisis ensues, including inflation of up to 1,000 % in certain areas of the empire.
- Fan Hsiung, aka Pham Hung, came to power in Champa and raided the Chinese-occupied territory of Tonkin.
- The Kingdom of Aksum (modern Ethiopia) begins minting its own gold coins to facilitate international trade, following the model of Roman coinage.
- Anthony the Great, a Christian saint from Egypt, regarded as Father of All Monks, enters the wilderness to become ascetic.
- The Chinese invent gunpowder (black powder), a mixture of sulfur, charcoal and potassium nitrate. It appears to have first been used only for fireworks.
- November 20 – Maximinus II, Roman Emperor
- Saint Nicholas (Santa Claus) (d. 343)
- Rabbah bar Nahmani, Babylonian 'amora
- Saint Spyridon, bishop of Trimythous (d. 348)
- St. Valentine (executed by Claudius II) (Possible year)
- Claudius II, Roman Emperor (b. 213)
- Quintillus, Roman emperor
- Plotinus, father of Neo-Platonism (b. c. 205) (approximate date)
- Jingu of Japan, possibly legendary empress of Japan
- Luo Xian, general of the Kingdom of Shu
- Qiao Zhou, minister of the Kingdom of Shu (b. 201)