The original version has been lost, but its content has been preserved in the rímur of Hrómundr Gripsson, known as Griplur, which were probably composed in the first half of the 14th century, but survived only in younger manuscripts and first appeared in print in 1896 in Fernir forníslenzkar rímnaflokkar, edited by Finnur Jónsson.
[2][3][4][5] The seventeenth-century saga contains a number of narrative discrepancies, which are probably the result of the scribe working from a partly illegible manuscript of the rímur.
[7]Hrolf of Skalmarnes told a saga about Hrongvid the Viking and about Olaf King of Warriors, and breaking into Thrain’s burial mound, and Hromund Gripsson—and many verses along with it.
When Hrómundr arrives, Helgi accidentally cuts off the swan's leg as he swings his sword, and is no longer protected by Kára's magic.
It is probably not a historic account of real events since it was remarked by king Sverre of Norway, who heard it, that it was an amusing "lying tale" (lygisaga).
This means that he would have lived in Norway in the first half of the 8th century, and it's not impossible that stories about an ancestor who did exist were handed down by his Icelandic descendants (probably becoming increasingly embellished as time passed).
A number of Scandinavian ballads appear related to the story and one of them served as an inspiration for a Viking metal song, Ramund hin unge by Týr.