The Dragon King of the Eastern Sea supplies one of the best known set pieces in Journey to the West, and it happens before Sun Wukong ever becomes a Buddhist pilgrim's protector. Newly born from stone and dissatisfied with his weapons, the Monkey King travels to the dragon's undersea crystal palace and demands something worthy of him; the reluctant king, unable to satisfy him with ordinary halberds or swords, is finally pressed into surrendering an immovable iron pillar used to gauge the depth of the Milky Way, an implausibly heavy rod that shrinks and grows at its wielder's command. Sun Wukong takes it as his signature weapon, the ruyi jingu bang, and the dragon king, humiliated and out a treasure, later joins his brother kings in petitioning heaven for the monkey's punishment, setting much of the novel's early plot in motion.
The episode fixes the standard folk picture of a Dragon King as wealthy, courteous under pressure, and ultimately outmatched by the story's real protagonist, and it is this scene, more than any temple ritual, through which most modern readers first encounter the Dragon Kings at all. The novel repeats the pattern with the other three sea kings later in the story, each drawn into supplying, losing, or arbitrating over some contested treasure, so that the entire family of Dragon Kings functions in the text less as objects of devotion than as a wealthy, slightly comic aristocracy whose court etiquette and grievances give the pilgrims recurring trouble on their journey west.