Arkadia
- Alea, Arkadia
- Heraia, Arkadia
- Kleitor, Arkadia
- Mantineia, Arkadia
- Megalopolis
- Orchomenos, Arkadia
- Pheneos, Arkadia
- Phlious, Phliasia
- Psophis, Arkadia
- Stymphalos, Arkadia
- Tegea, Arkadia
Heraia signs a treaty with Eleian cities for mutual protection and support for 100 years.
Sparta defeats Tegea and compels them to recognize their supremacy.
The Battle of Thermopylae. Soldiers from Sparta, Mantinea, Tegea, Orchomenos (Arkadia), Corinth, Phlious, Thespiai, Phokis, Opuntian Lokris, and other cities are overrun by the Persians at a huge cost.
Tegea is defeated by Sparta.
Sparta deposits hostages at Orchomenos, but when the army of Athens approaches, they are quickly given up.
King Agis of Sparta falls sick at Heraia. He is brought back to Lakedaimon, where he dies.
The Temple of Athena Alea in Tegea burns down.
July
Sparta and their allies, including Sikyon and Tegea, defeat Athens and their allies at the Battle of Nemea. On Athens side are Thebes, Lokris Opuntii, and Corinth. With Sparta are Halieis, Sikyon, Epidauros, Troizen, and Hermione. Phlious remains neutral. Pellene fights on the side of Sparta against Thespiai.
Sparta uses the Peace of Antalkidas to break Mantineia into multiple villages.
Mantineia is defeated by Sparta and the city is destroyed and split up.
Phlious accepts exiles from their city under threat from Sparta.
Agesilaos of Sparta lays siege to Phlious.
Sparta finally takes Phlious after a siege of 20 months, resets the government, and creates a new constitution.
Kleitor is at war with Orchomenos.
Megalopolis is founded by the Arkadian League as a counterweight to Sparta.
The Spartans in Tegea are expelled and Tegea joins the Arkadian League.
The territory of Heraia is laid waste by Arcadian cities due to Heraia’s support for Sparta.
The Theban general Epaminondas intervenes in Arcadia to support the Arcadian League and the newly founded city of Megalopolis. Heraia is pressured to join the Arcadian League but maintains a pro-Spartan stance.
Arkadians under Aineas of Stymphalos march to Sikyon and send Euphron into flight.
Dissolution of the Arkadian League, which had previously founded Megalopolis.
Sparta attempts to destroy Megalopolis, but the city is rescued by Thebes.
King Agis III of Sparta revolts from Macedonia and besieges Megalopolis, forcing Antipater to act.
April
Antipater defeats the Spartans under Agis III at Megalopolis. The Macedonians take many casualties, but Agis is killed.
Polyperchon issues a decree to restore democratic governments in all cities to reduce the allure of Kassander. Those exiled due to this may return, with the exception of Amphissa, Pharkadon, Herakleia Pontika, Trikka, and Megalopolis.
Polyperchon fails to take Megalopolis in a siege, which emboldens other cities against him.
Apollonides, a general of Kassander, takes Stymphalos.
Orchomenos is taken by Kassander from Polyperchon.
Demetrios Poliorketes seizes Epidauros, Sikyon, Corinth, Bura, Argos, and Orchomenos.
Heraia joins the Aetolian League.
Aristodamos the Good is installed as Tyrant of Megalopolis by Antigonos II Gonatas.
The Spartans under Akrotatos invade Megalopolis, but are defeated by Aristodamos the Good. Akrotatos is killed.
Aristodamos the Good, the tyrant of Megalopolis, is assassinated and the city returns to a democracy.
Lydiades becomes tyrant of Megalopolis.
Orchomenos is taken by Kleomenes III of Sparta.
Lydiades steps down as tyrant of Megalopolis and joins the city to the Achaian League.
Orchomenos switches from the Aetolian League to the Achaian League.
The Spartans under King Kleomenes III defeat the Achaian League under Aratos of Sikyon (and including Argos and Megalopolis) in the Battle of Dyme.
Mantineia is sacked by Antigonos III Doson. The city is handed over to Aratos of Sikyon, who repopulates it and renames it to Antigonia.
Orchomenos is occupied by the Macedonians under Antigonos III Doson, who places a garrison there.
Tegea is taken by Antigonos II Doson and annexed to the Achaian League.
Kleitor repulses an attack by the Aetolian League.
All of Tegea, except the Akropolis, is taken by the Spartan general Lykorgos.