100 BC

By place

Roman Republic

• Consuls: Lucius Valerius Flaccus, Gaius Marius.
• Manius Aquillius celebrates an ovation for victories in the Second Servile War.
• Lucius Appuleius Saturninus, a tribune, passes a law to redistribute land to military veterans. The law requires that all senators swear to abide by it. Quintus Caecilus Metellus Numidicus refuses and is exiled. He goes to Rhodes to study philosophy.
• Late summer–autumn: Saturninus stands for tribune again for the following year, and is elected. His associate, the praetor Gaius Servilius Glaucia, attempts to stand for the consulship. A rival candidate, Gaius Memmius, is found murdered by agents of Saturninus and Glaucia, who are declared public enemies by the Senate. The Senate issues the senatus consultum ultimum, and Marius, as consul, defeats his former ally in battle in the Forum. Saturninus and his followers surrender on condition that their lives are spared, but they are stoned to death with roof tiles in the Curia Hostilia by renegade senators.
• The building of the Sanctuary of Fortuna Primigenia, Palestrina, Italy, is begun. The model of it is now kept at the Museo Archeologico Nazionale, Italy.

  Asia Minor

• Tigranes II of Armenia is placed on the Armenian throne by the Parthians in exchange for the cession of "seventy valleys".

  Judea

• The deuterocanonical books of 1 and 2 Maccabees are written.

  Middle East

Asia

• Peasants revolt under Emperor Wu of Han. The Great Wall is extended out into the Gobi Desert, and sections of the wall are detached with signalling towers.
• Gandhara and Punjab are ruled by the Indo-Greek king Demetrius III Aniketos.
• A History of China is written by Sima Qian.

  America

• Mural room in the Maya pyramid at San Bartolo, Guatemala, painted.