|339 by topic|
|Ab urbe condita||1092|
|Balinese saka calendar||260–261|
|Chinese calendar||戊戌年 (Earth Dog)|
3035 or 2975
— to —
己亥年 (Earth Pig)
3036 or 2976
|- Vikram Samvat||395–396|
|- Shaka Samvat||260–261|
|- Kali Yuga||3439–3440|
|Iranian calendar||283 BP – 282 BP|
|Islamic calendar||292 BH – 291 BH|
|Minguo calendar||1573 before ROC|
|Seleucid era||650/651 AG|
|Thai solar calendar||881–882|
465 or 84 or −688
— to —
466 or 85 or −687
Year 339 (CCCXXXIX) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Claudius (or, less frequently, year 1092 Ab urbe condita). The denomination 339 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 Constantius II hastens to his territory in the East, where a revived Persia under King Shapur II is attacking Mesopotamia. For the next 11 years, the two powers engage in a war of border skirmishing, with no real victor.
- Pope Julius I gives refuge at Rome to the Alexandrian patriarch Athanasius, who is deposed and expelled during the First Synod of Tyre (see 335).
- Eusebius of Nicomedia is made bishop of Constantinople, while another Arian succeeds Athanasius as bishop of Alexandria, under the name Gregory.
- Aurelius Ambrosius, bishop of Milan (approximate date)
- He Fani, empress of the Jin Dynasty (d. 404)
- Shi Shi, emperor of the Jie state Later Zhao (d. 349)
- Abaye, Babylonian amora
- Eusebius of Caesarea, bishop and first church historian (approximate date)
- Shemon Bar Sabbae, bishop of Seleucia-Ctesiphon
- Wang Dao, statesman of the Jin Dynasty (b. 276)