The name of the region, like neighbouring Carinthia and Carniola (and quite possibly also Kras or Carso), probably derives from the Carni, a Celtic tribe who had lived for centuries in the fertile plains between the Rhine and the Danube rivers where other Celtic peoples lived. Starting from 400 BC, the demographic growth and the pressure of the Germanic peoples, originated a migratory flood towards the south. The Carni crossed the Alps via the Plöcken Pass and settled in the region which is nowadays named Carnia and in the piedmont zone of Friuli. They practiced hunting and breeding. During the hard winters the herders used to move with their cattle down to the piedmont plains. Also they were skilful iron and wood manufacturers. The Carni were headed by a king and a sacerdotal caste of druids.