I finished the first of the five-book spree of Paizo setting material that I picked up, Heart of the Jungle, which I presume is titled as an homage to Joseph Conrad's Heart of Darkness which was the mother of all jungle adventure stories, and wildly influential (along with H. Rider Haggard) on the developing pulp aesthetic jungle stories by guys like Robert E. Howard (Conan and others), Edgar Rice Burroughs (Tarzan and others), Talbot Mundy, and even George Lucas (Indiana Jones).
As expected, Heart of the Jungle is primarily about adventuring in the jungle in general, and the jungles of the Mwangi Expanse in the Pathfinder setting in particular. There is an interesting discussion about the hazards of jungle travel, including lots of new diseases, parasites, predators, and more. There is a bunch of setting stuff about the locations and cultures in the Mwangi jungles. Perhaps a bit surprisingly (or perhaps not, if you really think about it) there are even more references to lost civilizations deep in the jungle... ruined cities, temples, and degenerate descendents of once noble imperialists.
This isn't discussed in any great detail (this is, after all, only a 60 some odd page book, and the Mwangi Expanse is the equivalent of many nations in terms of size and diversity) but there's enough here to get you going for quite awhile, including, to use a few examples, the Aspis Consortium's corrupt trading city, a city ruled by an undead child-god who wants to drive all foreign elements from the land, a city ruled by a demonic gorilla and his demon-tainted apes, a crashed flying city, a number of cities that appear to possibly harbor unknown Lovecraftian entities buried beneath their depths, and more. In fact, anyone who was even a little familiar with my wildly successful Demons in the Mist Pbp game will know that I stole the idea of the gorilla nation wholesale from the Paizo campaign setting (although at the time, there wasn't any detail around it at all except that there was this gorilla kingdom deep in the jungle that exterminated any human(oids) who wandered into its territory.)
Paizo included a number of partial page maps of a number of cities, but only a few of them were actually professional cartographic representations of the kind they normally use, while the rest were, they claimed, designed to represent the kinds of hearsay and dubious maps you might find from hucksters and would be guides at some of the outpost towns here and there in the area; stuff that would prompt you to go to the jungle, but give you dubious benefit once you're there. They were designed to be player handouts and aides, although in that task, I'm a little curious how well they'd really work, especially since some of them straddle the spine of the book. Curious and potentially neat idea; I'm not sure if they have yet perfected the execution of it here, though.
An inordinate amount of text was given early in the book to promulgating the Avatar myth, i.e., the idea that anyone from a vaguely Europeanesque civilization can only be there to exploit, pillage and ultimately destroy the native lands. (This idea is much older than Avatar, the James Cameron movie, of course, but I call it that because it's the most prominent purveyor of that myth most recently.) This strong emphasis early on seems fundamentally at odds with much of the rest of the book which characterizes the jungle as ultimately untamed and untameable, a raw force of nature that will ultimately triumph over the pathetic attempts of mankind to conquer it. I suppose this can possibly be chalked up to having more than one writer, probably working independently on different parts of the book. In any case, once you get past several pages of that vibe, it tends to fade away, and the book becomes much more useful again. In fact, I found much of the book very interesting indeed, and while it offers much more in the way of capsule ideas that will then still need an awful lot of GM development to be workable, I find that's OK. Many of the Pathfinder Modules will give you more specifics on certain areas, and otherwise, I like making stuff up on my own anyway. But, I also like having idea minefields that I can scour for the kernels of ideas to develop, and this book certainly is that.
I was tempted to turn next to the Sargava book as a companion piece, what with Sargava being the neighboring region in the setting, and presumably a nice companion to this one. And I will eventually, but first I picked up Classic Horrors Revisited, so that'll be on my gaming reading cycle for the next little while.