420 BC

Calendar year

Millennium:	1st millennium BC
Centuries:	6th century BC 5th century BC 4th century BC
Decades:	440s BC 430s BC 420s BC 410s BC 400s BC
Years:	423 BC 422 BC 421 BC 420 BC 419 BC 418 BC 417 BC

Politics
420 BC by topic
State leaders Political entities
Categories
v t e

420 BC in various calendars
Gregorian calendar	420 BC CDXX BC
Ab urbe condita	334
Ancient Egypt era	XXVII dynasty, 106
- Pharaoh	Darius II of Persia, 4
Ancient Greek era	90th Olympiad (victor)¹
Assyrian calendar	4331
Balinese saka calendar	N/A
Bengali calendar	−1012
Berber calendar	531
Buddhist calendar	125
Burmese calendar	−1057
Byzantine calendar	5089–5090
Chinese calendar	庚申年 (Metal Monkey) 2278 or 2071 — to — 辛酉年 (Metal Rooster) 2279 or 2072
Coptic calendar	−703 – −702
Discordian calendar	747
Ethiopian calendar	−427 – −426
Hebrew calendar	3341–3342
Hindu calendars
- Vikram Samvat	−363 – −362
- Shaka Samvat	N/A
- Kali Yuga	2681–2682
Holocene calendar	9581
Iranian calendar	1041 BP – 1040 BP
Islamic calendar	1073 BH – 1072 BH
Javanese calendar	N/A
Julian calendar	N/A
Korean calendar	1914
Minguo calendar	2331 before ROC 民前2331年
Nanakshahi calendar	−1887
Thai solar calendar	123–124
Tibetan calendar	阳金猴年 (male Iron-Monkey) −293 or −674 or −1446 — to — 阴金鸡年 (female Iron-Rooster) −292 or −673 or −1445

Year 420 BC was a year of the pre-Julian Roman calendar. The denomination 420 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

Greece

The young and popular Alcibiades is elected "Strategos" (one of a board of ten generals) and begins to dominate Athenian life and politics. A Quadruple Alliance of Athens, Argos, Mantineia and Elis, which has been organised by Alcibiades (in opposition to Nicias) confronts a Spartan-Boeotian alliance.
Around 420 BC, Spartans were excluded from participating in the Olympic Games due to their ongoing conflicts with other Greek city-states, violating a peace treaty. This exclusion was part of a broader effort to maintain the peaceful atmosphere of the games.^[1]