| Millennium: | 1st millennium BC |
|---|---|
| Centuries: | 4th century BC – 3rd century BC – 2nd century BC |
| Decades: | 270s BC 260s BC 250s BC – 240s BC – 230s BC 220s BC 210s BC |
| Years: | 243 BC 242 BC 241 BC – 240 BC – 239 BC 238 BC 237 BC |
| 240 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 240 BC |
| Ab urbe condita | 514 |
| Armenian calendar | N/A |
| Bahá'í calendar | -2083 – -2082 |
| Bengali calendar | -832 |
| Berber calendar | 711 |
| Buddhist calendar | 305 |
| Burmese calendar | -877 |
| Byzantine calendar | 5269 – 5270 |
| Chinese calendar | [[Sexagenary cycle|]]年 (2397/2457) — to —
[[Sexagenary cycle|]]年(2398/2458) |
| Coptic calendar | -523 – -522 |
| Ethiopian calendar | -247 – -246 |
| Hebrew calendar | 3521 – 3522 |
| Hindu calendars | |
| - Bikram Samwat | -183 – -182 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 2862 – 2863 |
| Holocene calendar | 9761 |
| Iranian calendar | 861 BP – 860 BP |
| Islamic calendar | 887 BH – 886 BH |
| Japanese calendar | |
| Korean calendar | 2094 |
| Thai solar calendar | 304 |