Humans are one of the species endemic to the Fadelands. They originated in Verandi, but spread out to the three Brother Nations under the leadership of The Smith, who transformed humanity from living in isolated villages to large feudal kingdoms that would eventually feature major metropolitan centres such as New Vanover or Castle.
By the time of the campaign, most humans live in Vistria or Laric, with small populations in Korstraad (mostly either Vistrian farmers or nomadic tribesmen) and Tarq. There are also humans in the Shadowfel, but not much is known about them. There are more-or-less functional "nations" in some of the Vampire Kings' realms who pay "taxes" to their lords in the form of humans for use as vampire-feeding livestock, this being a more hands-off form of human farming than running a ranch of human cattle. The Mount Pillar Lich formerly lived in a village that was part of the Drow's surface territory, however that village was subsequently destroyed and its inhabitants (presumably) massacred.