This name derives from the Old English (Anglo-Saxon) element “*arōnan”, which in turn derives from the Proto-Norse and Proto-Germanic “*erōnan”. An earl is a member of the nobility. The title is Anglo-Saxon, akin to the Scandinavian form jarl, and meant "chieftain", particularly a chieftain set to rule a territory in a king's stead. In Scandinavia, it became obsolete in the Middle Ages and was replaced with duke (Hertig / Hertug). According to Procopius, the Heruli, after having raided the European continent for several generations, returned to Scandinavia in 512 AD as a result of military defeats. As their old territory was now occupied by the Danes, they settled next to the Geats in present-day Sweden. While the Proto-Norse word for this mysterious tribe may have been “erilaz”, which is etymologically near "jarl" and "earl", and it has often been suggested they introduced the runes in Scandinavia, no elaborate theory exists to explain how the word came to be used as a title.