The Foreword shows us the wealth of the author's sources and also that this text is more firmly embedded in the relevant literature than would usually be expected of an adventure novel published as a paperback:
"...all skaldic poetry translated in this book, including Harald's own, is authentic." (p. 11)
Anderson quotes some of the same sources as for his historical fantasies, eg, Saxo Grammaticus, but in the Trilogy of which The Golden Horn is Book 1, as in The Golden Slave and Rogue Sword, he presents straight historical fiction so:
"...Saxo's yarn of Harald's fight with a dragon is pretty clearly mythical, and therefore omitted..." (p. 12)
- whereas a fight with a dragon is included in Three Hearts And Three Lions because that novel is a heroic fantasy. As I have said before, Anderson was a master of all the genres. And The Golden Horn is good to read after completing Rogue Sword.