But let's go back in time. Near the end of the second millennium B.C. great cultural changes took place in Iberia, but many unanswered questions stand about the hows and by whoms. Traces of Central European bronze culture first appeared in the north. Probably not long after that introduction the first Indo-Europeans arrived. According to Bosch Gimpera, the first Celts may have arrived by 900 B.C., bringing small groups of Germans with them. Other Iberian authors state that the earliest Indo-Europeans were pre-Celtic Bronze Age people who arrived in Iberia about the year 1000 B.C. and were followed by other Bronze Age, pre-Celtic Indo-Europeans, the Urnfields people. Yet another historian, Almagro, doesn't distinguish between Urnfields, Ligurian, Illyrian, and Celt, and suggests that after 800 B.C. the Indo-European peoples integrated Iberia during a considerable amount of time and that they were essentially of the same source. Others will add more complexity to these theories. Anyway, taking aside the obscurity about certain details we still can conclude that there were movements of Central European peoples into Iberia during the late Bronze Age, either we classify these peoples as Celts or pre-Celts. These earliest Indo-Europeans, Celt or not, were not acquainted with the use of iron. The introduction of this metal is to be credited to the Goidelic Celts of the seventh century.

We also know that early Celts entered the peninsula through the western passes of the Pyrenees and they left their marks on the north of Iberia. Still, even if Celts find their way through what we now call the Basque area, in the present Spanish provinces of Vizcaya, Guipúzcoa, and Navarra, there is no record of Celtic dominance... It looks like the local population and culture were strong and they resisted, or transformed the Celtic influence. This will be different in Santander, León, or, Asturias, and even more in present northwest Portugal and Galicia.

Briefly, Celtic culture and language spread from southern France throughout most of the north of Iberia and on the west extended in the south including the Lusitanians of (the actual) central Portugal. In some spots they reached the Mediterranean coasts.

Most probably soon after the arrival of the first iron-using Celts, they re-established connections between the peninsula, western France, and the British Isles.