Galician legend holds that the Celtic King Breogan of Iberia and his sons sailed northwards and encountered an island. One of the sons then severed his own right hand and threw it ashore so that he could be remembered as the first person to touch the unknown land. This island was later to become known as Eire.
The Celts are widely believed to have been present on the Iberian peninsular around 900 BC. However, as you can guess over the centuries the celtic racial influence has been diluted almost beyond recognition (until my arrival of course).
Unfortunately good archaeolgical data on the subject is scarce. This is because the celtic practice of burning the dead has resulted in the absence of burial sites, thus depriving archaeologists of a vital source of data. Researchers therefore have difficulties in distinguishing celtic remnants from those of other races that pre dated their arrival.
The Celts were pastoral by nature, cooked with lard, drank fermented wheat beer and are credited with introducing the wearing of trousers to the peninsula. Place names ending in "-riga" are believed by academics to be celtic in origin as is unsurprisingly the spanish word for beer, "cerveza ".