|Millennium:||1st millennium BC|
|Centuries:||3rd century BC – 2nd century BC – 1st century BC|
|Decades:||160s BC 150s BC 140s BC – 130s BC – 120s BC 110s BC 100s BC|
|Years:||134 BC 133 BC 132 BC – 131 BC – 130 BC 129 BC 128 BC|
|131 BC by topic|
|Gregorian calendar||131 BC|
|Ab urbe condita||623|
|Bahá'í calendar||−1974 – −1973|
|English Regnal year||N/A|
|Chinese calendar||己酉年 (Earth Rooster)
2566 or 2506
— to —
庚戌年 (Metal Dog)
2567 or 2507
|Coptic calendar||−414 – −413|
|Ethiopian calendar||−138 – −137|
|- Vikram Samvat||−74 – −73|
|- Shaka Samvat||N/A|
|- Kali Yuga||2971–2972|
|Igbo calendar||−1130 – −1129|
|Iranian calendar||752 BP – 751 BP|
|Islamic calendar||775 BH – 774 BH|
|Minguo calendar||2042 before ROC
|Thai solar calendar||413|
|Wikimedia Commons has media related to 131 BC.|
Year 131 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Mucianus and Flaccus (or, less frequently, year 623 Ab urbe condita). The denomination 131 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Aristonicus of Pergamon leads an uprising against Rome, and consul Publius Licinius Crassus Mucianius is killed in the fighting.
- The Roman censor Quintus Caecilius Metellus Macedonicus attempts to remove the tribune Gaius Atinius Labeo Macerio from the Senate, the angry Atinius drags him to be thrown off the Tarpeian Rock, and Metellus is only saved by the intervention of other senators.
- The tribune Gaius Papirius Carbo passes a measure allowing the use of secret ballots in legislative assemblies.
- For the first time in Roman history, both censors are plebeians (Metellus and Quintus Pompeius).
- First Acta Diurna appears in Rome around this time.