This article concerns the period 349 BC – 340 BC.

• Sidon is besieged by Persian forces.

• After recovering from illness, Philip II of Macedon turns his attention to the remaining Athenian controlled cities in Macedonia and to the city of Olynthus, in particular. The Athenians organise to send help.

• After being besieged by the Persian forces of King Artaxerxes III, Sidon is taken and its population is punished with great cruelty.

• The Athenian help to its cities in Macedonia is diverted by a revolt in Euboea which Philip II of Macedon has fomented. He conquers the city of Olynthus in the Chalcidice and he annexes Chalcidice to Macedonia.
• The city of Eretria on the island of Euboea successfully rebels against the rule of Athens and Euboea is declared independent. The Athenian statesman and general, Phocion's tactical skills save an Athenian force sent to fight the supporters of Philip II on Euboea.
• Aristotle leaves Athens and Plato's Academy, after which he resided in Assus in northwestern Anatolia.^[1]

• Rome and Carthage make a trade agreement under which Carthage will not attack those Latin states which are faithful to Rome. This agreement demonstrates that Rome is now the dominant power in the Latin League.

• In the wake of the Macedonian victory at Olynthus, Athens seeks to make peace with Macedonia. Because his financial policy is based on the assumption that Athens should not be involved in major wars, the Athenian leader, Eubulus, works for peace with Philip II of Macedon. Demosthenes is among those who support a compromise.^[2]
• An Athenian delegation, comprising Demosthenes, Aeschines and Philocrates, is officially sent to Pella to negotiate a peace treaty with Philip II. During the negotiations, Aeschines seeks to reconcile the Athenians to Macedonia's expansion into Greece. Demosthenes became unhappy with the result.^[2]

• Coinage is introduced into Rome for the first time.^[3]

• Plato dies and his nephew Speusippus is named as head of the Academy.^[4]
• Aristotle leaves Athens due to the anti-Macedonian feeling that arises in Athens after Philip II of Macedon has sacked the Greek city-state of Olynthus in 348 BC. With him goes another Academy member of note, Xenocrates of Chalcedon. They establish a new academy on the Asia Minor side of the Aegean Sea at the newly built town of Assus.^[5]

• The Peace of Philocrates is signed between Macedonia and Athens. The document agrees to a return to the status quo, but Philip II of Macedon keeps the right to punish the Phocians for starting the Sacred War.
• The Athenian politicians, Demosthenes and Timarchus, prepare to prosecute Aeschines for treason after he has sought to reconcile the Athenians to Macedonia's expansion into Greece. Eubulus loses his influence on Athenian affairs.
• Demosthenes, though condemning the terms of the Peace of Philocrates, argues that it has to be honoured.
• Following the conclusion of the Peace of Philocrates, Philip II's army moves through the pass of Thermopylae and subdues Phocis. Athens makes no move to support the Phocians.

• Dionysius II is restored to power in Syracuse.

• Supported by Thebes and Thessaly, Macedonia takes over Phocis' votes in the Amphictyonic League, a Greek religious organisation formed to support the greater temples of Apollo and Demeter. Despite some reluctance on the part of the Athenian leaders, Athens finally accepts Philip II's entry into the Council of the League. The Athenian statesman Demosthenes is among those who recommend this stance in his oration On the Peace.

• The Nanda Empire is founded in Magadha.

• Carthaginians ravage and blockade Entella.

• The king of Caria, Idrieus, dies, leaving the Persian satrapy, by his will, to his sister Ada, to whom he was married.

• Philip II of Macedon besieges Perinthus, which had defied him and was inclining towards his opponents the Athenians, the Perinthian's allies Byzantium and the Achaemenid Empire support Perinthus in their defence of the city.^[6]
• Philip divides his army, leaving one part to besiege Perinthus and taking the other to besiege Byzantium.^[6]
• The Athenian statesman, Demosthenes, travels to Peloponnesus, in order to detach as many cities as possible from Macedon's influence, but his efforts are generally unsuccessful. Most of the Peloponnesians see Philip II as the guarantor of their freedom, so they send a joint embassy to Athens to express their grievances against Demosthenes' activities. In response to these complaints, Demosthenes delivers the Second Philippic, which is a vehement attack against Philip II.

• The aristocracy of Syracuse appeal to their mother city of Corinth against their tyrant Dionysius II. The Corinthian general Timoleon is chosen to lead a liberation force to Sicily. Landing at Tauromenium (Taormina) on March 21st, Timoleon faces two armies, one under Dionysius and the other under Hicetas (tyrant of nearby Leontini), who has also called in Carthaginian forces. By shrewd tactics Timoleon defeats his enemies and occupies Syracuse.
• Dionysius II goes into exile once more after the successful invasion by Timoleon of Corinth.

• The Greek philosopher and scientist, Aristotle, travels from Assus to Lesbos to study natural history, especially marine biology.

• The King of Persia, Artaxerxes III, personally leads the Persian forces invading Egypt. The Persians are keen to access Egypt's gold and corn supplies. The town of Pelusium in the Nile Delta puts up resistance, but Pharaoh Nectanebo II is forced to retreat to Memphis.^[7] As the situation deteriorates, Nectanebo II leaves for exile in Nubia. His departure marks the end of the 30th Dynasty, the last native house to rule Egypt.
• With Nectanebo II's flight, all organised resistance to the Persians collapses, and Egypt is once again reduced to a satrapy of the Persian Empire. A Persian satrap is put in place in Egypt. The walls of the country's cities are destroyed and its temples are plundered. Artaxerxes and his commander-in-chief, General Bagoas, leave Egypt loaded with treasure.

• The Athenian statesman Demosthenes has Aeschines indicted for treason. However, Aeschines drags up the inappropriate past of one of Demosthenes' associates, Timarchus and is acquitted by a narrow margin.
• King Philip II of Macedon again marches against Cersobleptes, King of Thrace, defeats him in several battles, and reduces him to the condition of being a tributary.
• Phalaikos unsuccessfully lays siege to Kydonia on the island of Crete.^[8]

• The native Italian tribes, the Lucanians and Bruttians, press down upon the Greek colonies of Magna Graecia, including Tarentum. Responding to calls for help from these former Greek colonies, King Archidamus III of Sparta sets sail with a band of mercenaries for Italy.
• After his surrender to the Corinthian general Timoleon, who takes over as ruler of Syracuse, the former tyrant, Dionysius II, is allowed to retire to Corinth to live in exile, although he dies within the year. The Syracusan constitution is changed by Timoleon with the new constitution designed to have safeguards against tyranny. Timoleon invites new settlers from Greece to come to Sicily.

• First Samnite War began when Rome fought the confederated Samnites over disputed territory in the Middle Liris Valley.^[9]

• The Greek philosopher, Aristotle, is invited by Philip II to his capital at Pella to tutor his son, Alexander. As the leading intellectual figure in Greece, Aristotle is commissioned to prepare Alexander for his future role as a military leader. (or 343 BC)^[10]
• Philip begins a series of campaigns in Thrace with the aim of annexing it to be a province of Macedonia. When the Macedonian army approaches Thracian Chersonese (the Gallipoli Peninsula), an Athenian general named Diopeithes ravages this district of Thrace, thus inciting Philip's rage for operating too near one of his towns in the Chersonese. Philip demands his recall. In response, the Athenian Assembly is convened. Demosthenes convinces the Athenians not to recall Diopeithes.

• The Corinthian general Timoleon spreads his rule over Sicily, removing a number of other tyrants and preparing Sicily for another threatened Carthaginian invasion.

• The Battle of Mount Gaurus is fought between the Romans and the Samnites. The battle is a success for the Romans, who, it is said, are led by Marcus Valerius Corvus. Fought at the foot of Mount Gaurus, near Cumae, it is the most notable engagement of the First Samnite War.

• In the course of the Warring States period, the army of the state of Qi defeats the army of the state of Wei in the Battle of Maling. This battle involves the military strategy of the general Sun Bin (descendant of Sun Tzu), and is the first battle in recorded history to give a reliable account of the handheld crossbow with trigger mechanism.

• Philip II of Macedon completes his annexation of Thrace. This is regarded by Athens as a further threat to the city's safety.

• Demosthenes delivers his Third Philippic. In it, he demands resolute action against Philip II. Demosthenes now dominates Athenian politics and is able to considerably weaken the pro-Macedonian faction led by Aeschines. As a result, Demosthenes becomes controller of the Athenian navy.
• A grand alliance is organised by Demosthenes against Philip II, which includes Byzantium and former enemies of Athens, such as Thebes. These developments worry Philip and increase his anger towards Demosthenes. The Athenian Assembly, however, lays aside Philip's grievances against Demosthenes' conduct and denounces the Peace of Philocrates which has been signed by both sides in 346 BC, an action equivalent to an official declaration of war by Athens against Macedonia.

• The First Samnite War ends with Rome triumphant and the Samnites willing to make peace.^[11]

• Rhodes falls to Persian forces.
• Pixodarus, the youngest of the three sons of King Hecatomnus of Caria, gains possession of the satrapy of Caria by expelling his sister Ada, the widow and successor of her brother Idrieus.

• When King Philip II of Macedon invaded Perinthus and Byzantium, King Artaxerxes III of Persia sent support to those cities.
• Philip II fails in his siege of Byzantium and is forced to respond to attacks by the Scythians near the mouth of the Danube. His son, Alexander is regent while his father fights against Byzantium and the Scythians.
• The Athenians give Demosthenes a public vote of thanks after Philip's unsuccessful siege of Byzantium.
• c. Derveni papyrus in a nobleman's grave in a necropolis of Lete.^[12]

• Hicetas, the tyrant of Leontini, again persuades Carthage to send a large army to Sicily, which lands at Lilybaeum. Timoleon of Syracuse meets this large Carthaginian army in the Battle of the Crimissus in the west of Sicily and achieves a brilliant victory against superior odds. Despite this victory, the Carthaginians continue to occupy the western half of Sicily, with a treaty being concluded that confines the Carthaginians to the area west of the Halycus (Platani) River.

• An embassy is sent by the Latin peoples to the Roman Senate asking for the formation of a single republic between Rome and Latium, in which both parties would be considered to be equal. As Rome considers that it is the leader of the Latin League, it refuses to treat the Latin people as being equal politically, or to have Latin people in the Roman Senate. With Rome's refusal of the proposal, the Latin War begins. The Latins fight with the Campanians, while Rome joins the Samnites to attack the Latins. Only the Laurentes in Latium and the equites of Campania remain with the Romans, who, for their part, find support among the Paeligni.
• The Roman-Samnite army under consuls Publius Decius Mus and Titus Manlius Torquatus attack and defeat the Latins and Campanians near Mount Vesuvius in the Battle of Vesuvius.^[13]
• The Romans succeed in detaching the Campanians from their alliance with the Latins (through their fear of the Samnites) and induce them to make a separate peace. Three Campanian cities, including Capua and Cumae, are granted Roman citizenship and thus become part of the Roman state. The Roman state now extends to the Bay of Naples.

343 BC

• Philetaerus, founder of the Attalid dynasty of Pergamum in Anatolia (approximate date) (d. 263 BC)

342 BC

• Menander, Greek playwright (d. 291 BC)

341 BC

• Epicurus, Greek philosopher was born in Samos^[14]

340 BC

• Appius Claudius Caecus, Roman politician and consul (approximate date)
• Chandragupta Maurya, founder of the Maurya Empire (approximate date)
• Qu Yuan, Chinese poet and minister (approximate date)

348 BC

• Plato, Greek philosopher and author^[1]

347 BC

• Archytas, Greek philosopher, mathematician and statesman (or 350 BC) (b. 428 BC)^[15][16]
• Plato, Greek philosopher and founder of the Academy in Athens (b. c. 427 BC)^[17]
• Eudoxus of Cnidus, Greek philosopher and astronomer who has expanded on Plato's ideas (or 355 BC) (b. 410 BC or 408 BC)^[18]

345 BC

• Nicochares, Athenian poet of the Old Comedy
• Mahanandin, last king of the Shishunaga dynasty of the Indian subcontinent.

344 BC

• Idrieus, king of Caria

343 BC

• Dionysius II, tyrant of Syracuse (b. c. 397 BC)

342 BC

• Pang Juan, Chinese general
• Antiphon, Greek arsonist, execution

340 BC

• Lais of Hyccara, Greek hetaira (courtesan) (approximate date)
• Mentor of Rhodes, Greek mercenary and satrap (approximate date)
• Xuan of Chu, Chinese king of Chu (Warring States Period)