| Millennium: | 1st millennium |
|---|---|
| Centuries: | 1st century – 2nd century – 3rd century |
| Decades: | 90s 100s 110s – 120s – 130s 140s 150s |
| Years: | 120 121 122 – 123 – 124 125 126 |
| 123 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 123 CXXIII |
| Ab urbe condita | 876 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1721 – -1720 |
| Bengali calendar | -470 |
| Berber calendar | 1073 |
| Buddhist calendar | 667 |
| Burmese calendar | -515 |
| Byzantine calendar | 5631 – 5632 |
| Chinese calendar | 壬戌年十一月十七日 (2759/2819-11-17) — to —
癸亥年十一月廿六日(2760/2820-11-26) |
| Coptic calendar | -161 – -160 |
| Ethiopian calendar | 115 – 116 |
| Hebrew calendar | 3883 – 3884 |
| Hindu calendars | |
| - Bikram Samwat | 179 – 180 |
| - Shaka Samvat | 45 – 46 |
| - Kali Yuga | 3224 – 3225 |
| Holocene calendar | 10123 |
| Iranian calendar | 499 BP – 498 BP |
| Islamic calendar | 514 BH – 513 BH |
| Japanese calendar | |
| Korean calendar | 2456 |
| Thai solar calendar | 666 |
Year 123 (CXXIII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar.