Candy Kingdom

The Candy Kingdom is a kingdom that was made and is ruled by Princess Bubblegum. It is made entirely of sweets and sugar, and is the most popular and recurring kingdom in the series. It seems to be the world power nation of the Land Of Ooo due to the fact its the biggest, developed kingdom and it's interest of other affairs around Ooo. The Candy People are the citizens that live there, most of them resembling some sort of candy or other sweet. Parties and major celebrations are thrown constantly here; this may be the Candy Kingdom's culture, or Princess Bubblegum's own positive personality. Lady Rainicorn, Tree Trunks and Pig are the only ones not to be candies or sweets.

Princess Bubblegum's Castle
This is the main center/castle of the Candy Kingdom where their ruler Princess Bubblegum lives, along with other Candy People.

Physical composition
Nearly everything in the Candy Kingdom is made of some kind of candy, including the ground which is made of peanut brittle as shown in "Susan Strong." Even the dirt is chocolate as seen in "Too Young."

It was revealed in "Burning Low" that the Candy Kingdom also owns territory that is not candy, as Princess Bubblegum was collecting taxes from Finn and Jake's Tree Fort.

Despite being a kingdom with living candies, it still has candies and sweets to eat. The distinction (as Finn explains in "Susan Strong") is that "You can't eat the ones that talk! They're special...they got aspirations."

As revealed in "The Vault," the kingdom primarily was built with a castle out of cake with the frosting applied later to give the more confectionary appearance. Beneath the kingdom is likewise a river of radioactive sludge which can harm and mutate anyone who falls within it, as what ultimately happens to Shoko.

Military
It is unknown whether or not the Candy Kingdom has been in any war or battle, however, the candy military seems to have advanced significantly over the course of the show. In the episode "Susan Strong," it is shown that the Candy Castle has an armory full of candy weapons. In the episode "Princess Cookie" it was revealed the Candy Kingdom has candy helicopters, which seems to be a large technological advantage over any other kingdom, although the true efficiency of candy weapons has yet to be tested.

The Candy Kingdom also maintains the Banana Guard, whose primary role appears to be that of a police force. These seem to act in other parts of Land of Ooo other than the Candy Kingdom, as seen in "Davey" where they answer a call for the Grass Lands (however, it may be because a part of the Grasslands is owned by Princess Bubblegum) and arrest Jake (dressed like a robber), and in "Princess Potluck," they even go to the Ice Kingdom.

The Gumball Guardians also act as a main line of defense within the Candy Kingdom, appearing quite often just outside the walls. They can intercept any evil force that enters or goes nearby the Kingdom. They are shown to attack evil in the episodes "Slumber Party Panic," "Mortal Recoil," "Reign of Gunters," and "The Lich."

Trivia

 * As implied by Jake in "Susan Strong," the Candy Kingdom military is rather ineffective, only winning the battle against the Hyooman tribe by sheer luck because the Marshmallow Kids were accidentally set on fire by Jake when he sneezed into the fire. However, it has seemed to advance in Season 4, with candy cane rifles (as seen in "Hug Wolf") and candy helicopters.
 * Adam Muto has said that the Candy Kingdom is a "princessipality" due to the fact that it is ruled by a Princess instead of a King or Queen.
 * Finn nearly caused its destruction three times. First, when he opened a black hole in "The Real You." Second, when he showed Susan Strong the kingdom and she brought the other Hyooman tribe members to eat it. Third, when he released wolves in Princess Bubblegum's room in "Go With Me," endangering Princess Bubblegum's life.
 * Finn mentioned it had a church, signifying that there is religion in Ooo.
 * Like in most cities, there is a "bad" part of town. It can be found behind Princess Bubblegum's castle as seen in "Apple Thief." The Candy Tavern is located there, and it is full of criminals.
 * The Candy Kingdom is home to the Candy Kingdom Mental Hospital, where the very old and the mentally ill reside, playing games. It appears that Doctor Princess is an active staff member.
 * Gunter and his magic penguin army (temporarily) conquered the Candy Kingdom (and the rest of Ooo) in "Reign of Gunters."
 * In "All Your Fault," Finn states that Princess Bubblegum made the Candy Kingdom.
 * The Candy Kingdom is seen burning from Ice King's window in "Another Five More Short Graybles."
 * Some parts of the kingdom was built above a radioactive river, as shown in The Vault.