312 BC

250 BC in various calendars

Gregorian calendar	250 BC CCL BC
Ab urbe condita	504
Ancient Egypt era	XXXIII dynasty, 74
- Pharaoh	Ptolemy II Philadelphus, 34
Ancient Greek era	132nd Olympiad, year 3
Assyrian calendar	4501
Balinese saka calendar	N/A
Bengali calendar	−842
Berber calendar	701
Buddhist calendar	295
Burmese calendar	−887
Byzantine calendar	5259–5260
Chinese calendar	庚戌年 (Metal Dog) 2448 or 2241     — to — 辛亥年 (Metal Pig) 2449 or 2242
Coptic calendar	−533 – −532
Discordian calendar	917
Ethiopian calendar	−257 – −256
Hebrew calendar	3511–3512
Hindu calendars
- Vikram Samvat	−193 – −192
- Shaka Samvat	N/A
- Kali Yuga	2851–2852
Holocene calendar	9751
Iranian calendar	871 BP – 870 BP
Islamic calendar	898 BH – 897 BH
Javanese calendar	N/A
Julian calendar	N/A
Korean calendar	2084
Minguo calendar	2161 before ROC 民前2161年
Nanakshahi calendar	−1717
Seleucid era	62/63 AG
Thai solar calendar	293–294
Tibetan calendar	阳金狗年 (male Iron-Dog) −123 or −504 or −1276     — to — 阴金猪年 (female Iron-Pig) −122 or −503 or −1275

312 BC in various calendars

Gregorian calendar	312 BC CCCXII BC
Ab urbe condita	442
Ancient Egypt era	XXXIII dynasty, 12
- Pharaoh	Ptolemy I Soter, 12
Ancient Greek era	117th Olympiad (victor)¹
Assyrian calendar	4439
Balinese saka calendar	N/A
Bengali calendar	−904
Berber calendar	639
Buddhist calendar	233
Burmese calendar	−949
Byzantine calendar	5197–5198
Chinese calendar	戊申年 (Earth Monkey) 2386 or 2179     — to — 己酉年 (Earth Rooster) 2387 or 2180
Coptic calendar	−595 – −594
Discordian calendar	855
Ethiopian calendar	−319 – −318
Hebrew calendar	3449–3450
Hindu calendars
- Vikram Samvat	−255 – −254
- Shaka Samvat	N/A
- Kali Yuga	2789–2790
Holocene calendar	9689
Iranian calendar	933 BP – 932 BP
Islamic calendar	962 BH – 961 BH
Javanese calendar	N/A
Julian calendar	N/A
Korean calendar	2022
Minguo calendar	2223 before ROC 民前2223年
Nanakshahi calendar	−1779
Seleucid era	0/1 AG
Thai solar calendar	231–232
Tibetan calendar	阳土猴年 (male Earth-Monkey) −185 or −566 or −1338     — to — 阴土鸡年 (female Earth-Rooster) −184 or −565 or −1337

Events

By place

Seleucid Empire

• Ptolemy and Seleucus, the satrap of Babylonia, invade the satrapy of Syria. The resulting Battle of Gaza leads to a triumph for Ptolemy and Seleucus over Antigonus' son, Demetrius Poliorcetes ("sieger of cities"), who is captured but immediately released. Seleucus ceases his service to Ptolemy and returns to his former province, Babylonia. This event takes place on October 1 and becomes the starting point of the Seleucid era.

Sicily

• The Syracusans ask for help against their tyrant Agathocles from the Carthaginians, who, fearing for their own possessions in Sicily, send a large force to the island.

Roman Republic

• The Roman censor, Appius Claudius Caecus, a patrician, enters office and begins construction of the Appian Way (the Via Appia) between Rome and Capua. He also embarks on a program of political reform, including the distribution of the landless citizens of Rome among the tribes, which at this time constitute basic political units. Appius also admits sons of freedmen into the Roman Senate. He also asserts the right of freed slaves to hold office.
• Rome gets its first pure drinking water as engineers complete the first aqueduct into the city, the Aqua Appia.