Native Portuguese are an Iberian ethnic group and they form 95% of the whole population, whose ancestry is very similar to Spaniards and have strong ties with fellow Atlantic Arc countries like Ireland, British Isles, France and Belgium due to maritime trade dated as far back as the Bronze Age. These maritime contacts and the prevalence of R1b haplogroup as the main genetical marker of these countries suggest a common ancestry and cultural proximity. Other maritime contacts with the Mediterranean especially with Greeks, Phoenicians, Romans and Moors added some particular phenotypes in southern Portugal and particularly southern Spain (the Tartessos culture), making Portugal and north-western Spain a bridge between north-western Europe and the Mediterranean but maintaining the Atlantic character.