| Millennium: | 1st millennium |
|---|---|
| Centuries: | 1st century BC – 1st century – 2nd century |
| Decades: | 0s 10s 20s – 30s – 40s 50s 60s |
| Years: | 28 29 30 – 31 – 32 33 34 |
| 31 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 31 XXXI |
| Ab urbe condita | 784 |
| Armenian calendar | N/A |
| Assyrian calendar | 4781 |
| Bahá'í calendar | -1813–-1812 |
| Bengali calendar | -562 |
| Berber calendar | 981 |
| English Regnal year | N/A |
| Buddhist calendar | 575 |
| Burmese calendar | -607 |
| Byzantine calendar | 5539–5540 |
| Chinese calendar | 庚寅年十一月十九日 (2667/2727-11-19) — to —
辛卯年十一月廿八日(2668/2728-11-28) |
| Coptic calendar | -253–-252 |
| Ethiopian calendar | 23–24 |
| Hebrew calendar | 3791–3792 |
| Hindu calendars | |
| - Vikram Samvat | 87–88 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3132–3133 |
| Holocene calendar | 10031 |
| Iranian calendar | 591 BP – 590 BP |
| Islamic calendar | 609 BH – 608 BH |
| Japanese calendar | |
| Korean calendar | 2364 |
| Minguo calendar | 1881 before ROC 民前1881年 |
| Thai solar calendar | 574 |
Year 31 (XXXI) 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 Augustus and Seianus (or, less frequently, year 784 Ab urbe condita). The denomination 31 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.