The Salassi were a Celtic or Celticized Italic or Ligurian tribe whose lands lay on the Italian side of the Little St Bernard Pass across the Graian Alps to Lyons, and the Great St Bernard Pass over the Pennine Alps. The Romans finally defeated and enslaved many of them in 25 BCE, and founded the city of Augusta Praetoria Salassorum, modern Aosta, in their territory.
At the lower end of their territory were gold mines, which the Roman Republic took in 143 BCE. In 100 BCE, the city of Eporedia (modern Ivrea) was founded in the basin at the bottom of the area. Relations with the Romans were not uniformly peaceful; Strabo mentions that the Salassi robbed Julius Caesar's treasury and threw rocks on his legions on the grounds that they were making roads and building bridges. There may have been a Roman campaign against the Salassi in 35 or 34 BCE under Marcus Valerius Messalla Corvinus or Antistius Vetus.
For their last decade of freedom the Salassi (with some other, mainly Alpine, tribes subjugated by 14 BCE) were almost the only remaining groups not under Roman control in the Mediterranean basin. After the Battle of Actium in 31 BCE the Roman world was united under one ruler, Augustus, who could concentrate Roman forces against remaining holdouts. The end of independence for the Salassi came at the hands of Aulus Terentius Varro Murena in 25 BCE. Strabo records that two thousand Salassi were killed and all the survivors, nearly 40,000 men, women, and children, were taken to Eporedia and sold into slavery. However, some remained; an inscription found near the west gate of Augusta Praetoria Salassorum is a dedication to Augustus dated 23 BCE of a statue (?) by "the Salassi who had joined the colony from its beginning."
Varro founded a Roman colony in the territory of the Salassi, Augusta Praetoria Salassorum, a well-fortified city protected by two streams. In the ensuing centuries of Roman peace, the Salassi disappear from history.