 Since there are no Phoenician inscriptions in Britain, if traders visited the island, the Insular Celtic part of the theory depended on linguistic evidence.The 5th millennium is very early for Celtic-speakers in Britain, compared with other theories, and Mallory suggested a date of around 1000 BC.Vennemann's view of the establishment of megaliths is not supported by mainstream archaeologists, who view their construction as having a widespread local origin along Oceanic Europe or one that spread from Portugal long before the Bell Beaker or any possible Cardium culture influences from the Mediterranean.