| Centuries: | 6th century · 7th century · 8th century |
| Decades: | 600s 610s 620s 630s 640s 650s 660s |
| Years: | 636 637 638 639 640 641 642 |
| 639 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 639 DCXXXIX |
| Ab urbe condita | 1392 |
| Armenian calendar | 88 ԹՎ ՁԸ |
| Bahá'í calendar | -1205 – -1204 |
| Bengali calendar | 46 |
| Berber calendar | 1589 |
| Buddhist calendar | 1183 |
| Burmese calendar | 1 |
| Byzantine calendar | 6147 – 6148 |
| Chinese calendar | 戊戌年十一月廿二日 (3275/3335-11-22) — to —
己亥年十二月初二日(3276/3336-12-2) |
| Coptic calendar | 355 – 356 |
| Ethiopian calendar | 631 – 632 |
| Hebrew calendar | 4399 – 4400 |
| Hindu calendars | |
| - Bikram Samwat | 695 – 696 |
| - Shaka Samvat | 561 – 562 |
| - Kali Yuga | 3740 – 3741 |
| Holocene calendar | 10639 |
| Iranian calendar | 17 – 18 |
| Islamic calendar | 17 – 19 |
| Japanese calendar | |
| Korean calendar | 2972 |
| Thai solar calendar | 1182 |