Although there is evidence that some fortified settlements of Gipuzkoa were inhabited as early as the first half of the first millennium BCE, carbon dating suggests that most date from a more recent period (Buruntza is 2,475±75 years old and Intxur 2,030±80); in other words, most of the sites excavated date from the second half of the millennium, up to dates close to the first century CE.
It was in these more recent periods that the occupants of these forts show signs of a greater mastery of local resources and new technologies. They stored the harvested crops inside their relatively comfortable houses. They used a variety of tools for different tasks, and the discovery of glass beads and bracelets suggests that they traded with other groups.
It was precisely at this point of cultural consolidation, in or around the first end of the first millennium BCE, without any apparent problem or conflicts - at least to judge from the archaeological evidence - that these defensive sites, which had been occupied over hundreds of years, were abandoned. As yet we do not know where the occupants moved to. No items associated with the Roman period have been found at any of the sites excavated to date and no samples have been carbon dated later than the first century BCE.
The inhabitants my have moved to the scattered outlying settlements on lower ground which almost certainly accompanied these fortified nuclei (although no hard and fast evidence for them has yet been found).
It is possible that recent finds from the Roman era in various parts of Gipuzkoa, especially in Irun/Hondarribia and Zarautz, may shed some light on the final phase in our Prehistory.