A Caladan primitive was an individual who belonged to tribes that were considered 'native' to the mainly water based world. The primitives were descendants of the Zensunni migrations that traveled and stayed on the planet prior the Butlerian Jihad. Many parts of the Eastern Continent of Caladan were set aside for them as a type of reserved land.
Existing mainly on the Eastern Continent of the planet Caladan, the natives lived in the dense jungles that were especially prominent in the equatorial areas of that land mass. Many of the tribes were matriarchal in leadership, with the primitive folk people living in a non-agrarian, nomadic hunter-gatherer lifestyle. The primitives, who were based along primal warrior clans, preferred to remain hidden in stealth, as they defended the tribal group.
When the warriors would encounter a hostile group of Caladanian citizens, the primitives would usually move to denser jungle, or to higher ground, to get away from the invading humans. Only when pushed to warfare would the primitives attack, or use their deadly poison weapons.
Piers Harkonnen crash landed in their primitive tribal lands and met their leader, Tiddoc. They helped him defeat the Cymek Agamemnon. Ashamed of his reliance upon the help of the tribe, Harkonnen remained stranded on Caladan.
Over 10,000 years later, when Duncan Idaho and Paul Atreides were fleeing from the assassins of House Moritani from Grumman, they took refuge amongst the dense jungles of the Eastern land mass. There they met with Caladanian primitives, who at first regarded them with suspicion, but after some time, learned the true nobility of House Atreides, and helped the duo defeat their trackers.