Aggonoth was once known as the Cursed Lands before rule was consolidated around the great city-fortress of Aggonoth. Aggonoth is largely a theocracy, worshipping the demon lords of the Infernal Plane. It can be a brutal place, with those in high places living a life of twisted debauchery while captured slaves of all races toil in the mines and such, fueling Aggonoth's industries with brutal labor. Benevolence is rare in the lands of Aggonoth, and when it does happen, it's usually because the "kind" person has something to gain from it.
As far as racial composition goes, there are plenty of humans, along with the demons they summon, as well as the many orcish clans who have pledged themselves to the Church of the Black Hand. There are also the various lesser demons summoned and bound by the cultists (they're not quite powerful enough to summon the more powerful demons and demon lords), as well as a few undead laborers raised by necromancers following demons of undeath. Then there are the slaves, who are composed of a variety of races captured by the armies of Aggonoth, as well as people who would dare commit crimes of heresy against the Church of the Black Hand. Those who are not lucky enough to become slaves usually become sacrifices to summon demons to this world.
In terms of foreign policy, Aggonoth always has a need for slaves and the Church of the Black Hand is always eager to spread its dominance across the realms. However, they are not beyond reason, and will trade and even ally with other nations provided that they have something significant to gain from it and the deal works in their favor. If they prove to be uncooperative, then..well..the pits will be full of fresh meat and the demons will feast well tonight.