During the Pre-Roman Iron Age (500 BC – AD 1), native groups began migrating south, and the first tribal Danes came to the country between the Pre-Roman and the Germanic Iron Age, in the Roman Iron Age (AD 1–400). The Roman provinces maintained trade routes and relations with native tribes in Denmark, and Roman coins have been found in Denmark. Evidence of strong Celtic cultural influence dates from this period in Denmark and much of North-West Europe and is among other things reflected in the finding of the Gundestrup cauldron.