The year 133 BCE should have been a year of great triumph for Rome. Scipio Aemilianus had taken Numantia, thereby solidifying Rome's control of central Spain (it had already subdued the southern and eastern portions). The same year, Attalus III, king of Pergamum in Asia Minor (modern-day western Turkey), bequeathed his wealthy kingdom to Rome; this was a gift of immense fortune that was acquired without a single casualty. Yet 133 BCE is typically not remembered for these auspicious events, instead 133 BCE is most remembered for being the year Tiberius Gracchus's body was found floating dead in the Tiber River along with the bodies of his political supporters.

Tiberius Gracchus, a tribune of the plebs, and his adherents had been beaten to death on the Capitoline Hill, Rome's most sacred space. Despite the pleas of Gaius Gracchus, Tiberius's brother, the conservative faction of the senate which had incited the violence refused to surrender the body for burial. Adding to their abuse, they dragged the dead down to the riverside and threw their bodies into the Tiber, a final reminder of what would happen to those who defied their authority. Tiberius's murder was all the more vicious because as a tribune of the plebs his body was sacrosanct—to violate his body physically was a crime not only against a fellow citizen but also against the gods. For the first time under the Republic, not since the expulsion of the kings nearly four hundred years earlier, Romans decided that political violence was the answer to their disagreements. No one involved in the events surrounding the murder of Tiberius Gracchus in 133 BCE could have understood the full ramifications of their actions. This act of political violence ushered in over one hundred years of strife, upheaval, and civil war until the centuries's old traditions of the Roman Republic yielded to the autocracy of the Roman Empire.

Tiberius Gracchus was from a prosperous Roman family that had demonstrated its competence and patriotism over several generations. It was no surprise then that in 133 BCE Tiberius Gracchus was elected to the office of tribune of the plebs.