Oiasso, Oiasona or Oiarso was a Vascon Roman (Civitas) town located on the left bank of the Bidasoa estuary in the Bay of Biscay. Archaeological evidence unearthed recently pinpoints the core area of Oiasso in the old quarter of Irun (Gipuzkoa) by the Spanish-French border, where harbour and bath remains have been discovered. However, two other focuses in Cape Higuer and hermitage Ama Xantalen point to a wider complex outside the main nucleus.
Current view of the mouth of the Bidasoa.
The Vascones were a pre-Roman tribe who, on the arrival of the Romans in the 1st century, inhabited a territory that spanned between the upper course of the Ebro river and the southern basin of the western Pyrenees, a region that coincides with present-day Navarre, western Aragon and northeastern La Rioja, in the Iberian Peninsula. The Vascones are often considered ancestors of the present-day Basques to whom they left their name.
Coins of Arsaos, Navarre, 150-100 BC, showing Roman stylistic influence. British Museum.
Ptolemy, who listed the main cities of the Vascones.