The name is derived from the Illyrian tribe of the Histri (Greek: Ιστρών έθνος), which Strabo refers to as living in the region. The Histri are classified in some sources as a "Venetic" Illyrian tribe, with certain linguistic differences from other Illyrians.[4] The Romans described the Histri as a fierce tribe of pirates, protected by the difficult navigation of their rocky coasts. It took two military campaigns for the Romans to finally subdue them in 177 BCE. The region was then called together with the Venetian part the X. Roman Region of "Venetia et Histria". Per ancient definition the north-eastern border of Italy. Dante Alighieri refers to it as well, the eastern border of Italy per ancient definition is the river Arsia (Raša). The eastern side of this river was settled by the people whose culture was different to Histrian. Earlier influence of the Iapodes was attested there, while in some moment between the 4th century and the 1st BC, the Liburnians extended their territory and it became a part of Liburnia.[5] On the northern side, Histria went much further north and included the Italian city of Trieste and the region of Venezia-Julia. Today, Trieste and Venezia-Julia are not included in Istria for political reasons.
Some scholars speculate that the names Histri and Istria are related to the Latin name Hister, or Danube. Ancient folktales reported—inaccurately—that the Danube split in two or "bifurcated" and came to the sea near Trieste as well as at the Black Sea. The story of the "Bifurcation of the Danube" is part of the Argonaut legend. There is also a suspected link (but no historical documentation is available) to the commune of Istria in Constanţa, Romania.