In the 9th century poem Ynglingatal, there are several stanzas where the kings are said to be in "Hel's embrace".
Hägerdal (1994) doubts that Christian ideas were unknown in Scandinavia before the 11th century and he (1994:4) has pointed out that Borre and Skiringssal, in the part about the kings of Vestfold, were archaeologically important locations during the Viking Age but not later.
The text is important, among other things, because it constitutes (in Latin translation) an independent version of Þjóðólfr of Hvinir's Ynglingatal besides the text in Ynglinga saga in the Heimskringla.
Krag, Claus Ynglingatal og Ynglingesaga- en studie i historiske kilder (1991)