Joc-Duloc was a Class N planet believed to be located somewhere in the Oralian sector. (Star Trek: Pioneer)
The planet's alleged surface was barren and rocky. A highly charged atmosphere causes the planet to experience severe storms and constant lightning strikes. Due to volcanic activity, the planet also has rivers of lava throughout the surface. From descriptions in legends, some scholars claim that the planet should be labeled and class Y planet, but a classification of N fits more with Calok's description of the surface's atmosphere.
The planet was the mythical home of monks, who guarded the secrets left by the First Ones. According to Tyson Calok, he found the legendary planet and was taught by the monks, from whom he acquired special abilities, including his red eyes. ("Transfer).
According to legend, the Oppressors had searched for the planet for centuries and never found it. Many believed that it did not exist; that it was only a fable that had been created in the hope that some of the First Ones' knowledge had been left behind. Though some believe it was from monks of Joc-Duloc where the Oppressors acquired Mass Driver technology. ("Question of Loyalty")
In 2382, Calok revealed to Commander L'mar that he still feared the power of the First Ones, saying that only a fool would not be afraid of such power. He also suggested that they might still be some First Ones in the Oralian sector, and that Joc-Duloc was the source of that power. ("The Boolran Eye, Part 1", "For Better or Worse", "Dawn")
The human scholar Felix Adar was obsessed with the myths of Joc-Duloc and spent the majority of his life trying to find the mythical planet.
Apparently the planet was also the home of a creature of unknown origin and longevity, simply referred to as The Beast. ("The Forgotten Planet")