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Gundalia (ガンダルディア, Gandarudia) is the Gundalians' home world. The city is underground and has been ruled by Emperor Barodius' family for several generations. This is also home to some breeds of Bakugan, born from ancestors that left Vestroia. It is a wasteland. It appears to be a swamp. Most Bakugan on Gundalia are of the Darkus Attribute.

It was one of the two planets involved in the Neathian-Gundalian War along with Neathia.

As of the end of the war, the Gundalians are no longer enemies of Neathia. Ren Krawler, Nurzak, Mason, Lena, Zenet, and Jesse later become allies of Neathia and the Brawlers.

It also appears that the Gundalians and Neathians are very good friends now, seeing how well Paige and Rafe battle and work together. However, it appears that a few, like Anubias, still have evil and dark intentions.

In A Hero Returns, Barodius (reborn as Mag Mel) started to attack Gundalia to get his revenge against his former servants.

Also, prior to Mechtanium Surge, Gundalia was a monarchical government ruled by Emperor Barodius and his ancestors, but from Mechtanium Surge onwards, it appears to be a parliamentary democracy in the vein of most of Europe, Asia, and Africa along with Australia. Now its goverment, with Prime Minister Nurzak at charge, manages the planet.