Extract from Wikipedia:

Cernunnos is known from archaeological sources such as inscriptions and depictions, to have been worshipped in Gaul, Northern Italy (Gallia Cisalpina) and the southern coast of Britain. The earliest known probable depiction of Cernunnos was found at Val Camonica in Italy, dating from the 4th century BC, while the best known depiction is on the famous Gundestrup cauldron found on Jutland, dating to the 1st century BC. The Cauldron was likely to have been stolen by the Germanic Cimbri tribe or another tribe that inhabited Jutland as it is quite clearly from south east Europe