I would wonder if Eaters of the Dead by Micheal Crichton counts.. (well, "Eaters of the Dead: The Manuscript of Ibn Fadlan Relating His Experiences with the Northmen in AD 922"). Basically, Crichton has a debate with friend who gave a lecture that Beowulf was uninteresting. Crichton stated it was more to do with how it was presented and it ended up with him doing the book which he took the writings of Ahmad Ibn Fadlan who was a Muslim who travelled and wrote about his experiences in the 10th Century, with the epic of Beowulf by having him meet up with the Norse tribe and joining them to chronicle the adventure so..
If you want to count it as Historical with the monsters being how they are kinda presented as 'how lbn Fadlan sees these people' or as a fantasy story with barbarians vs monsters is up to you. Though you might find it a bit dull as as much as I love the work of Crichton, they are slow story based more then action based, and he often puts in stuff to make you wonder if it's all real or fantasy (like his first major hit 'the Andromeda Strain' being presented as a declassified report on the events around the discovery of a new with commentary and statements, mixed with real world articles and references.
The finally made a film version, where it was retitled 'the 13th Warrior' but I never bothered with it (Eaters of the dead film that is.. they didn't make Andromeda strain as 13th Warrior.. I got the original film version of Andromeda and it's good and really faithful (apart from one change) but didn't bother with the remake.. might someday but if its equally as faithful, what's the point of making a remake?
If you can get them, the Slayers Light novels by Hajime Kanzaka (with art by Rui Araizumi) which lead to a good Comic series, an Anime series, a film series etc. if you are unaware.. Light novels are.. mm.. I would compare them to Pulp novels or teen novellas maybe.
while it's a side track, it's one of these series where I can spend ages on the back lore and stuff, with the how view of dæmons ranking, magic etc... at times, some of the translations are... not bad but iffy (and how the anime series did make a few mistake which creates.. problems, even before you see some translation mistakes