400 BC

Millennium:	1st millennium BC
Centuries:	5th century BC – 4th century BC – 3rd century BC
Decades:	430s BC  420s BC  410s BC  – 400s BC –  390s BC  380s BC  370s BC
Years:	403 BC 402 BC 401 BC – 400 BC – 399 BC 398 BC 397 BC

400 BC in other calendars

Gregorian calendar	400 BC CCCXCIX BC
Ab urbe condita	354
Ancient Egypt era	XXVIII dynasty, 5
- Pharaoh	Amyrtaeus, 5
Ancient Greek era	95th Olympiad (victor)¹
Assyrian calendar	4351
Bengali calendar	−992
Berber calendar	551
Buddhist calendar	145
Burmese calendar	−1037
Byzantine calendar	5109–5110
Chinese calendar	庚辰年 (Metal Dragon) 2297 or 2237     — to — 辛巳年 (Metal Snake) 2298 or 2238
Coptic calendar	−683 – −682
Discordian calendar	767
Ethiopian calendar	−407 – −406
Hebrew calendar	3361–3362
Hindu calendars
- Vikram Samvat	−343 – −342
- Shaka Samvat	N/A
- Kali Yuga	2702–2703
Holocene calendar	9601
Iranian calendar	1021 BP – 1020 BP
Islamic calendar	1052 BH – 1051 BH
Julian calendar	N/A
Korean calendar	1934
Minguo calendar	2311 before ROC 民前2311年
Thai solar calendar	143–144

File:Distribution of Celts in Europe.png

Celtic influence in Europe 400 BC (blue and purple).

Year 400 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Esquilinus, Capitolinus, Vulso, Medullinus, Saccus and Vulscus (or, less frequently, year 354 Ab urbe condita). The denomination 400 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Events

By place

• Artaxerxes II King of Persia appoints Tissaphernes to take over all the districts in Asia Minor over which Artaxerxes II's brother Cyrus had been governor before his revolt.
• Xenophon's "Ten Thousand" make their way back to Greece, with most of the men enlisting with the Spartans. Xenophon's successful march through the Persian Empire encourages Sparta to turn on the Persians and begin wars against the Persians in Asia Minor.
• With the outbreak of the war between Sparta and the Persians, the Athenian admiral, Conon, obtains joint command, with Pharnabazus, of a Persian fleet.
• War breaks out between Sparta and Elis.
• The Carthaginians occupy Malta.
• London has its origins on a rise above marshy waters at the point where the Walbrook joins the River Thames. The Celtic king, Belin, rebuilds an earth wall surrounding a few dozen huts and orders a small landing place to be cut into the south side of the wall, along the river front, where a wooden quay is built (approximate date)
• Amyrtaeus of Sais successfully completes a revolt against Persian control by gaining control of all of Upper Egypt.
• The Olmec culture in Mesoamerica comes to an end as its city of La Venta is abandoned (approximate date).
• San Lorenzo Tenochtitlán is abandoned (approximate date).

By topic

• The catapult is invented by Greek engineers.
• The Mature classical period of sculpture ends in Ancient Greece and is succeeded by the fourth-century (Late Classical) period (approximate date).
• A model of the Acropolis of Athens is made. It is now kept at the Royal Ontario Museum in Toronto, Canada (approximate date).
• Theodorus from Phokaia in Asia Minor, builds the Tholos, the sanctuary of Athena Pronaia in Delphi (approximate date).
• Dionysius I, Greek tyrant of Syracuse, confiscates gold and silver coins re-mints it keeping the weight the same but changing the denomination from one to two drachmae — the first known official devaluation at the expense of the general population. A virulent inflation ensues (approximate date).
• Zoroastrianism becomes the faith of many Persians. The Zoroastrians believe in a struggle between their god, Mazda, and the devil. They believe that the birth of their founder, the prophet Zarathustra, was the beginning of a final epoch that is to end in an Armageddon and triumph of good and evil.
• Brahmanism starts evolving in Hinduism, a process which takes place over the following 200 years (approximate date).

Deaths

• Siddhārtha Gautama (also known as Buddha), founder of Buddhism (approximate date)
• Thucydides, Greek historian (approximate date) (b. c. 460 BC)
• Aspasia of Miletus, widow of Pericles of Athens (approximate date) (b. c. 470 BC)