// Workers AI · dad joke modeWhat did 321 say to 123? You're odd, I'm even.

This article is about the year 321. For the game show, see 3-2-1. For other uses, see 321 (disambiguation).

Roman sun god Sol Invictus

321 in various calendars

Gregorian calendar	321 CCCXXI
Ab urbe condita	1074
Assyrian calendar	5071
Balinese saka calendar	242–243
Bengali calendar	−273 – −272
Berber calendar	1271
Buddhist calendar	865
Burmese calendar	−317
Byzantine calendar	5829–5830
Chinese calendar	庚辰年 (Metal Dragon) 3018 or 2811     — to — 辛巳年 (Metal Snake) 3019 or 2812
Coptic calendar	37–38
Discordian calendar	1487
Ethiopian calendar	313–314
Hebrew calendar	4081–4082
Hindu calendars
- Vikram Samvat	377–378
- Shaka Samvat	242–243
- Kali Yuga	3421–3422
Holocene calendar	10321
Iranian calendar	301 BP – 300 BP
Islamic calendar	310 BH – 309 BH
Javanese calendar	202–203
Julian calendar	321 CCCXXI
Korean calendar	2654
Minguo calendar	1591 before ROC 民前1591年
Nanakshahi calendar	−1147
Seleucid era	632/633 AG
Thai solar calendar	863–864
Tibetan calendar	ལྕགས་ཕོ་འབྲུག་ལོ་ (male Iron-Dragon) 447 or 66 or −706     — to — ལྕགས་མོ་སྦྲུལ་ལོ་ (female Iron-Snake) 448 or 67 or −705

Year 321 (CCCXXI) was a common year starting on Sunday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Crispus and Constantinus (or, less frequently, year 1074 Ab urbe condita). The denomination 321 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.

Events

By topic

Roman Empire

• Emperor Constantine I expels the Goths from the Danube frontier and repairs Trajan's Bridge. He leads an expedition into the old province Dacia (modern Romania) and makes peace with the barbarians.
• March 7 - Constantine I signs legislation directing urban residents to refrain from work, and businesses to be closed, on the "venerable day of the Sun". An exception is made for agriculture.

Asia

• Tuoba Heru launches a coup d'état against his cousin Tuoba Yulü and becomes the new Prince of Dai.

By topic

Art and Science

• Calcidius translates Plato into Latin.

Food and Drink

• Constantine I assigns convicts to grind Rome's flour, in a move to hold back the rising price of food in an empire whose population has shrunk as a result of plague.

Religion

• The Christian Church is allowed to hold property.
• A synod held in Alexandria condemns Arianism.
• History of the Jews in Germany: Jews in modern-day Germany are documented for the first time, in Colonia Agrippinensium (modern-day Cologne).

Births

• Cheng of Jin (or Shigen), Chinese emperor (d. 342)
• Du Lingyang (or Chenggong), Chinese empress (d. 341)
• Valentinian I ("the Great"), Roman emperor (d. 375)

Deaths

• Tuoba Yulü, Chinese prince of the Tuoba Dai
• Zu Ti (or Shizhi), Chinese general and adviser (b. 266)