Etsch, anc. Athesis), a considerable river in North Italy.
The tenth region included Venetia from the Padus and Adriatic to the Alps, to which was annexed the neighboring peninsula of Istria, and to the west the territory of the Cenomani, a Gaulish tribe, extending from the Athesis to the Addua, which had previously been regarded as a part of Gallia Cisalpina.
It was an important point in the road system of the district, lying on that between Mediolanum and Aquileia, while here diverged to the north the roads up the Athesis valley and over the Brenner into Raetia, and to the south roads ran to Betriacum, Mantua and Hostilia.
The limits of their territory are not clearly defined, but were probably the Athesis (Adige or Etsch) on the east, the 0111us (Oglio, or perhaps the Addua) on the west, and the Padus on the south.