He was the author of the Prose Edda or Younger Edda and the Heimskringla , a history of the Norwegian kings that begins with legendary material and moves through to early medieval Scandinavian history . He was the author of the Prose Edda or Younger Edda , which consists of Gylfaginning ( `` the fooling of Gylfi '' ) , a narrative of Norse mythology , the SkÃ ldskaparmÃ l , a book of poetic language , and the HÃ ttatal , a list of verse forms . He was also the author of the Heimskringla , a history of the Norwegian kings that begins with legendary material in Ynglinga saga and moves through to early medieval Scandinavian history .