Land of the Cragnons
From the Super Mario Wiki
The Land of the Cragnons (called Crag by the Cragnons) is the setting of Chapter 5 in Super Paper Mario. Mario, Princess Peach and Bowser enter the light blue door. It is the home of the Cragnons, a prehistoric race of primitive people with televisions and stereo CD players, seemingly made of rocks. It is also home to the enemies of the Cragnons, the Floro Sapiens, who live underground with their king, who is the boss of Chapter 5.
The chapter this land takes place in, Chapter 5, is similar to the Chapter 5 in the original Paper Mario. In both chapters, Mario has to go into a mountain-like area (in Paper Mario is was Mt. Lavalava and here it was Mount Crag, or more accurately the Gap of Crag), they both featured a type of adventurer accompanying him during the Chapter (in Paper Mario, it was Kolorado, while in Super Paper Mario is was Flint Cragley), and both chapters had a plant boss (in Paper Mario it was Lava Piranha, while in Super Paper Mario it was King Croacus IV.) Mario also gets a kind of hammer in both areas (in Paper Mario, it was an Ultra Hammer, while in Super Paper Mario, he gets a hammer-like Pixl named Cudge.)
Near the end of the game during the final battle with Super Dimentio, the Land of the Cragnons is destroyed by The Void but is restored following the destruction of the Chaos Heart along with all other demolished worlds.