180 BC

By place

Greece

• After three years of intriguing against his younger brother Demetrius, including accusing him of coveting the succession to the Macedonian throne and being allied to Rome, Perseus persuades his father King Philip V of Macedon to have Demetrius executed.

  Roman Republic

• Rome completes its subjugation of all of Italy with the defeat of the Ligurians in a battle near modern Genoa. Rome deports 40,000 Ligurians to other areas of the Republic.
• Lucca becomes a Roman colony.

  Egypt

• Ptolemy VI Philometor, aged 6, rules as co-regent with his mother, Cleopatra I, who, although a daughter of a Seleucid king, does not take King Seleucus IV's side and remains on friendly terms with Rome.
• Following the death of Aristophanes of Byzantium, Aristarchus of Samothrace becomes librarian at Alexandria.

  Bactria

• Demetrius I starts his invasion of present-day Pakistan, following the earlier destruction of the Mauryan dynasty by general Pushyamitra Shunga.
• Apollodotus I, a general with Demetrius I of Bactria, becomes king of the western and southern parts of the Indo-Greek kingdom, from Taxila in Punjab to the areas of Sindh and possibly Gujarat. He maintains his allegiance to Demetrius I.

  China

• September 26 — Lü Clan Disturbance
• Emperor Wen of the Han dynasty ascends to the throne.
• The state of Nanyue in Vietnam and southern China submits to the Han dynasty as a vassal.