>>11
Well, maybe because in the first place, a celtic tribe lived in that region, the Celtiberians. Some Spanish and Portuguese words came directly from their celtic language, some others were celtic words that became part of Latin vocabulary and then evolved into Spanish/Portuguese. One example is "porcom", it was a Celtiberian word then it became "porcu" in Latin and then "porco" in Portuguese. The word for beer "cerveja" share it's roots with "crwr" which is Welsh for beer. In that case, Irish Gaelic didn't keep the celtic word for it and and adopted a Germanic word instead.