As to the fight with the dragon, Boer believes that it did not originally belong to the saga, for in none of the sources except the popular ballad is the fight with the dragon connected with the release of Brunhild. If the Siegfried-Hagen story is purely human, then the dragon cannot have originally belonged to it, but was later introduced, because of the widespread belief in the dragon as the guardian of treasure, and in order to answer the question as to the provenience of the hoard. This is, however, only one answer to the question. Another, widespread in German legends, is that the treasure comes from the Nibelungs, that is, from the dwarfs. Many identify the dwarfs and the dragon, but this finds no support in the sources, for here the dwarfs and Fafnir are never confused. The "Nibelungenlied" describes an adventure with each, but the treasure is only connected with the dwarfs. The "Thidreksaga" knows only the dragon fight but not the dwarfs, as is likewise the case with the Seyfrid ballad. Only in the Norse sources do we find a contamination. The story of Hreithmar and his sons, who quarrel about the treasure, resembles that of Schilbung and Nibelung in the "Nibelungenlied", and probably has the same source. One of the sons, because of his guarding the treasure, is identified with the dragon, and so we read that Fafnir becomes a dragon, after gaining the treasure. Originally, however, he was not a dragon, but a dwarf. These two independent forms can be geographically localized. The dwarf legend is the more southern; it is told in detail in the "Nibelungenlied". The dragon legend probably originated in the Cimbrian peninsula, where the "Beowulf" saga, in which the dragon fight plays such an important part, likewise arose.