The realm of Darkening Sun is ruled by five great kingdoms: Elf, Human, Dwarf, Orc and Mer. Each kingdom owns vast tracts of lands which its ruler may choose to grant to his subjects because of blood ties or in return for their loyalty and service, referred to as vassalage. A group of the king's subjects come together under a common cause under the service of their ruler to which they are bound. They become a clan.
A group may also come together without sanction from a kingdom. Most kingdoms consider this an affront to their rule however and these clans may find themselves hunted. Further, because they pledge no loyalty to a king they cannot own land and must remain a loose assemblage.
There is only one exception to this rule, the Mages of the Arcane who have existed longer than the kingdoms themselves.
Each kingdom has its own rules on the type of races and classes welcome to form clans within its walls. In turn each clan has rules which its member must follow.