A free A-Z Encyclopedia Hyboria (2019) by ‘bittertreememory’. His book is relatively mighty-thewed at 24,000 words, if you also paste the well-hidden Preface into a Word .DOC file. The Preface reveals that Encyclopedia Hyboria only covers the Howard works. Dipping in randomly, it seems to me like excellent and precise work.
I’d assume ‘bittertreememory’ is American, given his American spelling of encyclopaedia. Someone should try to contact him and get permission for an expanded book, adding…
* an additional introduction by a big name such as Roy Thomas;
* an introduction that surveys similar reference works if they exist, and/or any in-world reference files Howard developed for his own use;
* a short in-world story chronology of Howard’s Conan tales;
* story titles added to each entry, where relevant – see ‘at a glance’ where each item or character was used;
* abundant use of small illustrations in a suitably loose Kaluta/Frazetta sort of pen-and-ink style;
* add maps and then add runes that colour-code the entries by region;
* add a short scholarly survey of the most notable and faithful new items added by later writers of Conan tales;
* then design and print it up as a book.
Another option for such a book would be Dale E. Rippke’s online A Gazetteer Hyboria which is a 1,000-item A-Z that includes the pastiche books and the better comics of the 1970s and 80s. Though, by including the larger post-Howard Conan works, this would cause all sorts of copyright tangles for a new expanded book version.
The author states that about a third of A Gazetteer Hyboria, presumably the purist Howard-only items, had long ago appeared in print in the Borgo Press guide titled A Gazeteer of the Hyborian World of Conan (1977). Some sources have this as Starmont House, not Borgo. Possibly there was a hardback from Starmont, and a paperback from Borgo?
A Gazetteer Hyboria seems to have vanished from all but Archive.org, presumably for fear of copyright trolls, but Dale E. Rippke also has a live Solomon Kane Gazetteer v.2.0 (2015) online for free.
For additional non-people/places items, the 128-page gamer book GURPS Conan has a section titled… “A gazetteer featuring the people, customs, laws, religion, and mysteries of 34 lands in the world of Conan.”
Also noted recently, and also useful for fan-writers as well as gamers, the new Conan the Adventurer (Modiphius, 2020). This is a 120-page illustrated PDF sourcebook, described as…
the definitive guide to the lands south of the Styx River, including serpent-haunted Stygia, Kush, Darfar, Keshan, Punt, Zembabwei, and that vast region known to the folk of the Dreaming West as ‘the Black Kingdoms’.
Apparently the new book was… “developed with leading Conan scholars”, so is presumably largely ‘Howardian’ — rather than bolting on later developments in movies, videogames, cash-in novels, comics etc.
Modiphius previously published Conan: Nameless Cults, a sumptuous book and…
guide to the cosmology, gods, cults, and otherworldly entities of Conan’s world and time.