When discussing Celtic Europe, one must understand that a number of different nations were categorized as Celtic. Ireland, England, Scotland, Wales, Cornwall, the Isle of Man and Brittany (now part of France) were all considered Celtic, as was the Iberian peninsula of Spain. One unique feature of Celtic culture is its influence from having been invaded by two other completely different European cultures: the Vikings and the Romans. Somewhere around the first century AD, the Romans invaded England and attempted to establish military outposts there; remains of many Roman-built roads can be found throughout England. The Romans did not make it to Ireland which may account for a relative purity of spiritual traditions there, with paganism giving way eventually to Catholicism. The Viking invasions from Norway, Denmark and other Scandinavian countries took place around the 6th century, and definitely included Ireland as well as Scotland and England. It has been said that the genes of the Scandinavians and the Celts are very well-mixed because of these invasion activities, not least because the Vikings were said to have abducted Irish women to take onboard their ships.