Thidreks saga (also Thidreksaga, Thidrekssaga, Niflungasaga) is a saga of the adventures of the hero Dietrich von Bern, believed to be based on the historical Theodoric the Great, and written down about 1250.
The original is in Old Norse, believed to have been written down by a Norwegian, but it purports to be based on stories told to the writer by Germans. It is a source of some debate as to which parts of the story are based on German legend vs Norse legend, since there are many differences between this saga and the Nibelungenlied.
It should be noted that here, in the Thidrekssaga, the name Amelungs is referred to Erminrek and his family, who would later become enemies of Thidrek (Dietrich) of Bern.
Actually a whole chapter was devoted to Velent in the Thidrekssaga, which is very similar to the Icelandic poem Volundarkvida (Poetic Edda) – the "Lay of Volund".
There is great deal of similarities of this section of the Thidrekssaga with the Nibelungenlied, concerning the Fall of the Nibelungs.