Sometime between 400 and 500 AD, there was an increase in the amount of gold, as indicated by archeological excavations across northern Europe—this is likely related to the extensive use of Germanic mercenaries by the Romans as they attempted to expand their empire. Round gold medals inspired by Roman coins appeared, adorned by images of Balder, Tyr and Odin. These gods were prominently worshipped by the upper class and the Germanic kings. In this example, Roman techniques were used to reproduce and convey Germanic ideas and religion.