| Millennium: | 4th Millennium BC |
|---|---|
| Centuries: | 41st cent. BC – 40th cent. BC – 39th cent. BC |
| Decades: | 4000s BC 3990s BC 3980s BC – 3970s BC – 3960s BC 3950s BC 3940s BC |
| Years: | 3978 BC 3977 BC 3976 BC – 3975 BC – 3974 BC 3973 BC 3972 BC |
| Gregorian calendar | 3975 MMMCMLXXV |
| Ab urbe condita | 4728 |
| Armenian calendar | 3424 ԹՎ ՎՆԻԴ |
| Assyrian calendar | 8725 |
| Bahá'í calendar | 2131–2132 |
| Bengali calendar | 3382 |
| Berber calendar | 4925 |
| British Regnal year | N/A |
| Buddhist calendar | 4519 |
| Burmese calendar | 3337 |
| Byzantine calendar | 9483–9484 |
| Chinese calendar | 甲戌年 (Wood Dog) 6671 or 6611 — to — 乙亥年 (Wood Pig) 6672 or 6612 |
| Coptic calendar | 3691–3692 |
| Discordian calendar | 5141 |
| Ethiopian calendar | 3967–3968 |
| Hebrew calendar | 7735–7736 |
| Hindu calendars | |
| - Vikram Samvat | 4031–4032 |
| - Shaka Samvat | 3896–3897 |
| - Kali Yuga | 7075–7076 |
| Holocene calendar | 13975 |
| Igbo calendar | 2975–2976 |
| Iranian calendar | 3353–3354 |
| Islamic calendar | 3456–3457 |
| Japanese calendar | Heisei 1987 (平成１９８７年) |
| Javanese calendar | 3968–3969 |
| Juche calendar | 2064 |
| Julian calendar | Gregorian minus 28 days |
| Korean calendar | 6308 |
| Minguo calendar | ROC 2064 民國2064年 |
| Nanakshahi calendar | 2507 |
| Thai solar calendar | 4518 |
| Unix time | 63271670400–63303206399 |
The year 3975 BC