Editing 5th century BC (section)

===[[400s BC (decade)|400s BC]]===
* [[409 BC]]: Athens recaptures [[Byzantium]], thereby putting an end to its revolt against Athens and taking control of the whole [[Bosporus]].
* [[409 BC]]: The city of [[Rhodes]] is founded.
* [[409 BC]]: The Carthaginians invade [[Sicily]].
* [[408 BC]]: The Persian king, [[Darius II of Persia|Darius II]], decides to aid Sparta in the war and makes his son [[Cyrus the Younger|Cyrus]] a [[satrap]]. However, Cyrus starts collecting an army to benefit his own interests, rather than his father's.
* [[408 BC]]: [[Alcibiades]] returns to Athens in triumph after an absence of seven years.
* [[407 BC]]: The Athenian fleet is routed by the Spartan one in the [[Battle of Notium]], which gives Alcibiades' opponents a reason to strip him of command. He never returns to Athens again.
* [[406 BC]]: Athens defeats Sparta in the [[Battle of Arginusae]] and the blockade of [[Conon]] is lifted.
* [[406 BC]]: Sparta sues for peace, but Athens rejects this.
* [[406 BC]]: The [[Carthage|Carthaginians]] once again invade Sicily and return to Carthage with spoils of war, but also with the plague.
* [[405 BC]]: The Spartan king [[Pausanias of Sparta|Pausanias]] lays siege to [[Athens]], which makes the city start starving.
* [[405 BC]]: [[Dionysius the Elder]] rises to power in [[Syracuse, Sicily|Syracuse]]. He signs a peace with Carthage and starts consolidating and expanding his influence.
* April 25, [[404 BC]]: Athens surrenders to Sparta, ending the [[Peloponnesian War]]. Sparta introduces an oligarchic system, the [[Thirty Tyrants]], in Athens.
* [[404 BC]]: [[Ancient Egypt|Egypt]] rebels against Persian rule.
* [[403 BC]]: The Chinese state of [[Jin (Chinese state)|Jin]] is [[Partition of Jin|divided]] into three smaller nations.<ref name=Zhao2004>{{cite journal|last=Zhao|first=Dingxin|year=2004|title=Comment: Spurious Causation in a Historical Process: War and Bureaucratization in Early China|journal=American Sociological Review|volume=69|issue=4|pages=603–607|doi=10.1177/000312240406900407}}</ref>
* [[403 BC]]: The first [[hydraulic engineering]] in [[China]] for a large irrigation canal system is designed by [[Ximen Bao]].
* [[403 BC]]: Some exiled Athenians return to fight the Thirty Tyrants and restore democracy in Athens. They are, however, narrowly defeated by the Spartans in the [[Battle of Piraeus]]. After this, the Spartan king [[Pausanias of Sparta|Pausanias]] allows democracy to be restored in Athens.
* [[403 BC]]: [[Thrasybulus]] restores the Athenian democracy and grants an almost general amnesty.
* [[403 BC]]: The Athenians adopt the Ionian alphabet.
* [[401 BC]]: [[Cyrus the Younger]] rebels against the Persian king [[Artaxerxes II]] but is, however, eventually slain in battle.
* [[400 BC]]: After Cyrus has been killed, his Greek mercenaries make their way back to Greece, where Sparta is so impressed with their feats in and march through [[Persia]] that they declare war on the Persians.
* [[400 BC]]: The Carthaginians occupy [[Malta]].
* [[400 BC]]: The Egyptians successfully revolt against Persian rule.
* [[400 BC]]: [[London]] has its origins as far back as this time.
* [[400 BC]]: [[Jōmon period]] ends in [[Ancient Japan]].
* [[400 BC]]: The [[D'mt|Kingdom of D'mt]] is disestablished.