From the roman age and mixed with things earlier than it were discover in Duio parishes countless remains which witnessed the existence of an important population.
The celtic tribe of the nerios inhabit these lands and maybe in that plain zone of Duio they have their main settlement. From the suevos age we know a detail of a punishment assigned by the king Reckila to the city of Dugium, Duio in the medieval denomination, due that the inhabitants destroyed the celtic and arrians temples.
It was a cosmopolite city with a big harbour serving an intense commercial activity, ruled by the queen Lupa, who played an important and decisive play in the Apostle Santiago grave location due her refusal to let him be buried in her lands. From it there are conserved several an important deposits of tools, pottery, etc., as results of excavations done in the suppossed location of the city.