阴水蛇年 (female Water-Snake) −260 or −641 or −1413 — to — 阳木马年 (male Wood-Horse) −259 or −640 or −1412
Year 387 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Papirius, Fidenas, Mamercinus, Lanatus and Poplicola (or, less frequently, year 367 Ab urbe condita). The denomination 387 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Peace of Antalcidas (or "the king's peace") is brokered by Artaxerxes II. Under the Peace, all the Asiatic mainland and Cyprus remain under Persian control, Lemnos, Imbros, and Scyros remain Athenian dependencies, and all the other Greek states are to receive autonomy. By the King's Peace, the Persians become key players in Greek politics.
Under the threat of Spartan intervention, Thebes disbands its league, and Argos and Corinth end their shared government. Corinth is incorporated back into Sparta's Peloponnesian League.
With the aid of the Lucanians, Dionysius I of Syracuse devastates the territories of Thurii, Crotone, and Locri in mainland Italy. When Rhegium falls, Dionysius becomes the chief power in Greek Southern Italy. He then turns his attention to the Adriatic and founds the colonies of Ancona (Ankon) and Adria (Adrìa).
Plato is forced by Dionysius to leave Syracuse after having exercised the right of free speech too broadly. Plato returns to Athens, outside which he founds a school.
Roman Republic
Rome begins to rebuild after being invaded by the Gauls under Brennus.