| Millennium: | 2nd Millennium |
|---|---|
| Centuries: | 18th cent. – 19th cent. – 20th cent. |
| Decades: | 1830s 1840s 1850s – 1860s – 1870s 1880s 1890s |
| Years: | 1863 1864 1865 – 1866 – 1867 1868 1869 |
| Gregorian calendar | 1866 MDCCCLXVI |
| Ab urbe condita | 2619 |
| Armenian calendar | 1315 ԹՎ ՌՅԺԵ |
| Assyrian calendar | 6616 |
| Bahá'í calendar | 22–23 |
| Bengali calendar | 1273 |
| Berber calendar | 2816 |
| British Regnal year | 29 Vict. 1 – 30 Vict. 1 |
| Buddhist calendar | 2410 |
| Burmese calendar | 1228 |
| Byzantine calendar | 7374–7375 |
| Chinese calendar | 乙丑年 (Wood Ox) 4562 or 4502 — to — 丙寅年 (Fire Tiger) 4563 or 4503 |
| Coptic calendar | 1582–1583 |
| Discordian calendar | 3032 |
| Ethiopian calendar | 1858–1859 |
| Hebrew calendar | 5626–5627 |
| Hindu calendars | |
| - Vikram Samvat | 1922–1923 |
| - Shaka Samvat | 1787–1788 |
| - Kali Yuga | 4966–4967 |
| Holocene calendar | 11866 |
| Igbo calendar | 866–867 |
| Iranian calendar | 1244–1245 |
| Islamic calendar | 1282–1283 |
| Japanese calendar | Keiō 2 (慶応２年) |
| Javanese calendar | 1794–1795 |
| Julian calendar | Gregorian minus 12 days |
| Korean calendar | 4199 |
| Minguo calendar | 46 before ROC 民前46年 |
| Nanakshahi calendar | 398 |
| Thai solar calendar | 2408–2409 |
The year 1866 BC
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