151 BC

By place

Carthage

• The Carthaginian debt to Rome is fully repaid, meaning that, according to Carthage, the treaty with Rome, which was put in place at the end of the Second Punic War, is no longer in force. The Romans do not agree with this interpretation. Instead they view the treaty as a permanent declaration of Carthaginian subordination to Rome.
• Numidia launches another border raid on Carthaginian soil, besieging a town. In response Carthage launches a large military expedition to repel the Numidian invaders.

  Roman Republic

• At Polybius' request, Scipio Aemilianus manages to gain the support of the Roman statesman Cato the Elder for a proposal to release the 300 Achaean internees who are still being held without trial after being deported to Rome in 167 BC.
• Roman forces help the thriving Greek commercial port of Massilia combat raids from the Celts from Cisalpine Gaul.
• Roman armies under the leadership of praetor Servius Sulpicius Galba and the proconsul Lucius Licinius Lucullus arrive in Hispania Ulterior and begin the process of subduing the local population. The revolt of the Celtiberians of Numantia is stopped.

  India

• Agnimitra succeeds his father Pushyamitra Shunga as emperor of the Shunga dynasty.