Micipsa was the eldest son of king Massinissa of the Massylian (eastern) Numidians. He and his brother Gulussa are first heard of as ambassadors to Carthage, asking for the return of about forty pro-Numidian politicians who had been exiled and were living at the Numidian court. The embassy was unsuccessful: after the men had reached Carthage, they were sent away. Gulussa was even attacked, which led to retaliations and, eventually, the outbreak of open war between Numidia and Carthage.note[Appian, Punic Wars 70.] This happened in 150 BCE. Because Rome had forbidden Carthage to wage war, it was the direct cause of the Third Punic War.
Shortly after this war had broken out in 149 BCE, king Massinissa died (Spring 148).note[Livy, Periochae 50.7.] The Roman officer Scipio Aemilianus was the executor of his will
To Micipsa, the oldest, a lover of peace, he assigned the city of Cirta and the royal palace there. Gulussa, a man of warlike parts and the next in age, he made the director of matters relating to peace and war. Mastanabal, the youngest, who was learned in the law, was appointed judge to decide causes between their subjects.note[Appian, Punic Wars 106.]
Together with Mastanabal, Micipsa supported the Romans during the war against Carthage. However, our main source, Appian of Alexandria, remarks that Micipsa and Mastanabal were not completely reliable:
the sons of Massinissa were always promising arms and money to the Romans, but always delaying and waiting to see what would happen.note[Appian, Punic Wars 111.]
In the end, Micipsa was loyal and he remained loyal to Rome when the war was over. After Scipio Aemilianus had destroyed Carthage (146), the Roman general Quintus Fabius Maximus Servilianus, who was fighting a war against the Lusitanians and their commander Viriatus, asked Micipsa to send him some war elephants, which duly happened. In 142 BCE, he received at least ten elephants and three hundred Numidian horsemen.note[Appian, Spanish Wars 67.] It is probable that by now, Micipsa's two co-rulers had already succumbed to an illness, leaving him only ruler.note[Sallust, Jugurtha 5.6.]
Micipsa tried to increase the amount of cultivated land on the Hautes Plaines. Cirta became a real Hellenistic city:
Micipsa not only settled a colony of Greeks in it, but also made it so great that it could send forth ten thousand cavalry and twice as many infantry.note[Strabo, Geography 17.3.13.]
The presence of Italian settlers can be deduced from funerary steles from Hofra, immediately south of Cirta. A plague in 125 BCE, which was still remembered in the fifth century CE, took away many people in northern Africa, however.note[Livy, Periochae 60.4; Orosius, History against the Pagans 5.15.2; Obsequens, Omens 90.] It may have reached Numidia.
In 134, Micipsa sent his relative Jugurtha, a son of Mastanabal, to Spain, where Scipio Aemilianus was besieging Numantia. The Roman historian Sallust suggests that Micipsa did not trust his cousin and was hoping the young man would get killed.note[Sallust, Jugurtha 7.2.]
Instead, the young prince won great praisenote[Sallust, Jugurtha 9.1-2.] and was adopted by Micipsa (c.121 BCE).note[Sallust, Jugurtha 5.7.] In 118, Micipsa died, apparently suffering from dementia.note[Sallust, Jugurtha 11.5.] He was probably buried in the tomb at Soumaa d'el-Khroub, just south of Cirta, although an inscription mentions his statue in a funerary context in Iol Caesarea (modern Cherchell).
Jugurtha succeeded his uncle, together with Micipsa's sons Hiempsal and Adherbal;note[Livy, Periochae 62.2.] Both men were killed and Jugurtha became sole ruler in 112.