The Morindim were a tribe of Godless Ones (relatives of the Dals, the Ulgos, the Melcenes and the Karands) which were left over after the creation of the world. The Morindim traveled north and took up demon worship.
They used magic to summon demons from Hell.
They had no written language but instead communicated via "Markers" (Pestilence, Curse..) which could be put up around their territory.
When Garion, Belgarath and Silk travel through Morindim territory, they encounter a group of them. Belgarath refers to them as Headman of the Weasel Clan, White Braids (the magician) and the "dreamer".