T2b in Western Europe is often associated with wives of the Halstatt, Celtic expansion. If this is the case, it would have spread into Iberia with the Celts who later blended with the local population to become the Celtiberians.
One could logically assume that if there were actually a large ethnocultural migration that would follow in the wake of a spearhead of PIE warrior men rather than just wholesale slaughter of indigenous males. We can assume that those who followed in their wake would largely be blacksmiths attracted to the mineral rich Atlantic fringe of Europe. It was likely these, more permanent settlers, who brought with them T2b wives among others.