260

Year 260 (CCLX) was a leap year starting on Sunday of the Julian calendar.

• Battle of Edessa: Emperor Valerian is defeated by the Persians.
• Valerianus I has a meeting with Shapur to talk about peace. The truce is betrayed and he is taken prisoner for the rest of his life.
• Shapur I sends Valerian to Bishapur. The Roman army builds the Band-e Kaisar (Bridge of Valerian).
• Gallienus becomes the new emperor of Rome.
• Gallienus leaves the fortifications in the Black Forest area because of invading Alamanni.
• Gallienus lives at Mediolanum (modern Milan).
• Postumus, Roman usurper, forms the Gallic Empire.
• Saloninus, son of Gallienus, is made Augustus by his troops.
• Postumus kills Saloninus. He is made emperor.
• Postumus wins over all the Roman provinces west of the Alps, including Gaul, Britain and Hispania.
• The Roman fort of Wiesbaden (Germany) is captured by the Alamanni.
• The Franks take control over the Scheldt estuary (approximate date).

• Persian king Shapur I destroys Caesarea Mazaca in Asia Minor.
• Cao Huan succeeds Cao Mao as ruler of the Chinese Kingdom of Wei.
• Syria, Egypt and Palestine break off from the Roman Empire to form the Persian-supported Palmyrene Empire.

• Earliest known date of chess.

• Pope Dionysius makes bishop Dionysius of Alexandria explain why he is separating the members of the Trinity as three distinct gods.
• Paul of Samosata becomes Patriarch of Antioch.

• Jin Huidi, emperor of the Jin Dynasty (approximate date)
• Gaius Galerius Valerius Maximianus, Roman Emperor (d. 311)

• Cao Mao, ruler of the Chinese Kingdom of Wei (killed in an abortive coup d'état against Sima Zhao) (b. 241)
• Chen Tai, minister of the Kingdom of Wei
• Saloninus, Roman emperor and son of Gallienus
• Sun Liang, Emperor of the Chinese Kingdom of Wu (b. 243)
• Valerianus I, Roman emperor (approximate date)