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.
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.
Philip advanced to the conquest of the eastern districts about Hebrus, and compelled the submission of the Thracian prince Cersobleptes.
Coinage is introduced into Rome for the first time.
With the death of Archytas in 347 BC, the powerful city of Taranto started a slow, but unavoidable decline; the first sign of the city's decreased power was its inability to field an army, since the Tarentines preferred to use their large wealth to hire mercenaries, rather than leave their lucrative trades.
- The Greek philosopher Plato establishes the Academy. This free school dedicated to the god Academus is supported by philanthropists and will last for 876 years.
- Plato dies and his nephew Speusippus is named as head of the Academy.
- 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 BCE. 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.
- Roxana, the wife of Alexander the Great (approximate date) (d. 309 BC)
- Plato, Greek philosopher and founder of the Academy in Athens (b. c. 427 BC)
- Eudoxus of Cnidus, Greek philosopher and astronomer who has expanded on Plato's ideas (or 355 BC) (b. 410 BC or 408 BC)