The cult of the first dead, as they are fully called, are a cult of necromancers operating across Vlulera, the cult worships the "first of the dead", an ancient and powerful undead who was thankfully destroyed long ago.
There is much hypocrisy regarding viewpoints on the cult of the dead, with everyone stating they "despise the cult and its immoral practices" yet they turn to the aid of the cult in more than one war.
But even then, there are many sects dedicated to rooting out the cult, this can be seen in the hangings of major spellcasters across history for alleged ties to the cult and their necromantic practices. With very few of those spellcasters having any real ties to the cult.
One of the major themes the cult emphasizes is the concept of "souls", an otherworldly energy derived from the life force of individuals, weak or strong. Long ago undead used these souls to feign life for the briefest moment, and that it was also a key element to mageries.
Many of the members of this cult joined to master these souls, as this is one of the only clear ways to learn the arts of souls. The reasons for this vary themselves, some want to resurrect loved ones, others want power over others.
The cult of the dead also has an aptitude for pulling the strings behind bandit gangs and exceptionally aggressive tribes that they have gained control over. More inexperienced groups of this cult use more obvious servants, the undead.
Very few high ranking members of the cult have obtained a kind of "undead nirvana" in the form of a horrid ritual, this ritual involves the masters death at the hands of his subjects, and his soul manipulated by a peer into the corpse of another creature, the souls, depending on the amount of souls used in the ritual, it is successful, leading to the master becoming the much feared "banshee" as the bodies are combined, but this is rarely successful and just results in the loss of a master. They believe that this is the closest one can get to the power of the first of the dead.
Not all sects of the cult are evil, though, there is one that exists in the forest region who provides supplemental aid to the poor village they overlook. Whether or not this is a facade is unknown...
Ironically, the cult began with the help of a cleric, the first leader of the cult was a dryad named Radusk. His studies led him to a tomb long since missing. It can only be assumed that he uncovered knowledge of the first of the dead that either drove him insane or genuinely interested him. The enemies of the cult believe that this tomb is the main base of the cult. But Radusk was slain in the 3000th age.
It was certainly not the empire that slew him, it was in fact the empire that tried to prevent his death, as Radusk aided them in many wars behind the scenes as a source of knowledge.
Tribal lands are the most safe location for the cults bases, primitive tribes are easily swayed by their words and are also easily recruited as servants and cult initiates.
one of their largest enemies is the descendants of the Rannar clan, one of the yeti clans that first arrived, and made the cult their primary targets.
The cult also has a large standing in the ice capped mountains, where the isolation provides safety from foes and much-needed solitude for their studies.
A member of the ruling Cannan family also tried creating an undead army with the aid of soul magic after she was exiled for being a member of the cult.
The cult has recently claimed that the undead have created a kingdom of their own across the sea, which resulted in a mass migration of cult members that ended in their death overseas. But the cult still holds onto a hope that their lord, the first of the dead, actually still exists alongside the banshee of Radusk.