Royal Frankish Annals
In sources beginning with the Royal Frankish Annals, the Merovingian kings of the Franks traditionally traced their lineage through a pre-Frankish tribe called the Sicambri (or Sugambri), mythologized as a group of "Cimmerians" from the mouth of the Danube river, but who instead came from Gelderland in modern Netherlands and are named for the Sieg river.