This is another nation that I'm using without too much in the way of remixing. The biggest change is that of course my ruleset doesn't follow the D&D convention of "goblinoids" as a triracial conglomeration, and instead follows a more Tolkien-like biracial "orcs and goblins" convention. In Eberron, they make a fair bit of hay with the idea that orcs are totally different from, and have a bitter rivalry, with the goblinoids. But their orcs aren't really exactly like orcs as we're used to them, and their hobgoblins are. So, I've come up with a pretty simple solution: orcs and goblins in my system belong together, as they normally would in any system other than D&D, and orcs stand in for hobgoblins in every place where hobgoblins exist. On the other hand, what to do where Eberron has orcs? I've replaced them with Atlanteans, which seems to make sense because both are kind of savage peoples and both have a claim to possessions on the continent before the arrival of the Sarlonan humans. We'll get to Atlanteans more when we are in a place where they feature a bit more prominently; probably not until the Shadow Marches.
My system also doesn't have bugbears, but it does have thurses, which would normally be fairly conceptually and visually similar to a D&D bugbear. They don't actually play a very major role in Darguun, though, unless you're up in the Marguul clans area in the mountains.
A few other differences, mostly minor; Tuura Dhakaan, leader of the Kech Volaar, is a female bard. It doesn't actually make any sense to me that such a person would lead an orc tribe that value strength more than any other quality, so it'll be changed to chief Tuur Dhakaan, a warrior-chief of a more traditional mold, albeit one who is more intelligent and educated about orc and goblin heritage than most and hopes to lead not by simply intimidating everyone into following him but rather by inspiring them.
Finally, the Khraal rainforest is described as dangerous and the orcs and goblins don't go there much, and certainly don't live there; because it's so dangerous. Although what exactly makes it so dangerous is not ever stated. I'm going to say that a daemon-lord of sorts lives there—a kind of analog to King Kong—and has turned native apes and mandrills intelligent (albeit savage) tribe-cults who worship daemons, squat in the ruins of ancient Dhakaani cities, or maybe the occasional abandoned Cyran outpost, and generally make the place very difficult to live in. However, I'm also going to posit that there are untold riches of knowledge and possibly treasure in these ancient Dhakaani cities, as well as other natural resources, which will bring these apes and baboons into increasing conflict with others. I realize that that all sounds very Mwangi Expanse from Golarion, but that's OK, but it was a great idea when they did it, so why wouldn't it be a great idea here too?
I'll go ahead and do the racial breakdown; it's not quite as fully orc and goblin heavy as you might think, given that until recently this was Cyran territory. Many humans (and demihumans) still live here, often as a kind of helot class, or even outright slaves to the orcs and goblins, and a few manage to fend off the orcs, and have made a fragile peace with them, but are able to retain their traditional homelands, of sorts. And of course, there are all kinds of mercenaries, criminals, adventurers and others who have other reasons to come here, as detailed in the book itself.
Darguun population remixed
Goblin: 39%
Orc: 29%
Thurse: 13%
Human: 12%
Hyperborean: 4%
Other: 3%