Dragonkin

Dragonkin were a race that were fought by Robert the Strong. They made the Dragon armour and weapons.

The dragonkin were not immortal, but as close to immortal as a mortal could be. As a result of their mortality, Robert the Strong was able to fight the dragonkin, and end their tyranny.

Along with being mortal, dragonkin could not reproduce. To protect themselves and carry on their lineage they created a race of weaker clone beings that could reproduce... those clones are known today as Dragons.

During the A Tail of Two Cats quest, players are able to see a cutscene of Robert the Strong defeating a dragonkin.

Jagex has revealed that the Dragonkin storyline is to be expanded in further updates.

The King Black Dragon is supposedly a dragonkin, or in contact herewith them, and the metal dragons are supposedly the most powerful of the current dragons and were fashioned from metal for the dragonkin's protection.