1st century BC

thumb|550px|Map of the world in 100 BC, the beginning of the first century BC

thumb|550px|Map of the world in 50 BC

thumb|550px|Map of the world in 1 AD, shortly after the end of the first century BC

The 1st century BC, also known as the last century BC and the last century BCE, started on the first day of 100 BC and ended on the last day of 1 BC. The AD/BC notation does not use a year zero; however, astronomical year numbering does use a zero, as well as a minus sign, so "2 BC" is equal to "year –1". 1st century AD (Anno Domini) follows.

In the course of the century, all the remaining independent lands surrounding the Mediterranean Sea were steadily brought under Roman control, being ruled either directly under governors or through puppet kings appointed by Rome. The Roman state itself was plunged into civil war several times, finally resulting in the marginalization of its 500-year-old Roman Republic, and the embodiment of total state power in a single man—the Roman emperor.

The internal turbulence that plagued Rome at this time can be seen as the death throes of the Roman Republic, as it finally gave way to the autocratic ambitions of powerful men like Sulla, Julius Caesar, Mark Antony and Octavian. Octavian's ascension to total power as the emperor Augustus is considered to mark the point in history where the Roman Republic ends and the Roman Empire begins. Some scholars refer to this event as the Roman Revolution.

In the eastern mainland, the Han dynasty began to decline and the court of China was in chaos in the latter half of this century. Trapped in a difficult situation, the Xiongnu had to begin emigration to the west or attach themselves to the Han.

Events

90s BC

thumb|upright|[[Sulla's march on Rome in 88 BC was an early step in the Crisis of the Roman Republic.]]

97 BC: Ariarathes VIII is forced out of Cappadocia by Mithridates VI of Pontus, and dies soon afterwards.
96 BC: Cyrene is left to the people of Rome by its ruler Ptolemy Apion.
96 BC: King Alexander Jannaeus of Judea wins the Siege of Gaza.
95 BC: Tigranes the Great becomes king of Armenia
93 BC: Ariobarzanes I Philoromaios becomes king of Cappadocia with Roman backing.
91 BC: The assassination of Marcus Livius Drusus leads to the Social War (91–87 BC) in Italy
91 BC: Crown Prince Ju Revolt in China.

80s BC

thumb|upright|[[Mithridates VI of Pontus]]

thumb|upright|Coin of [[Maues]]

thumb|alt=Burebista|Dacian king [[Burebista]]

89 BC: Mithridates VI of Pontus's invasion of Cappadocia leads to the First Mithridatic War with the Roman Republic.
89 BC: Valagamba of Anuradhapura gains control of all of Sri Lanka
88 BC: 80,000 Roman civilians killed in the Asiatic Vespers in Asia Minor
87 BC: Emperor Wu of Han dies and is succeeded by his eight-year-old son Zhao, with Jin Midi, Shangguang Jie and Huo Guang as regents.
88 BC: Sulla becomes the first Roman general in history to march on Rome