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- For the 1980s version of this location, see Thundera.
Thundera was a kingdom on Third Earth that was built by the Cats. The ThunderCats, being the royal family, rule the kingdom. They live in a huge palace that is shaped like a giant sitting cat. The Lord of the ThunderCats, Claudus was the King of Thundera until his death, after which Lion-O inherited the throne.
The Cats are the main residents of Thundera. Most of them live a luxurious life. Some of the poorer ones live in the slums of Thundera, along with a few Dogs. Apart from the Cats, all the other animal species that live in Thundera have a very hard life characterized by destitution and constant harassment at the hands of the Cats.
The Cats did not believe in technology, and as such nothing mechanical or electrical can be found in Thundera. Even the Thunderian Soldiers were armed with crude weapons.
Despite all these shortcomings, peace reigned on Thundera until Claudus' general, Grune betrayed him and sided with Mumm-Ra and his Lizard army. The villains, armed with high-tech weapons were able to easily defeat the Thunderian soldiers and laying waste to the kingdom. Many were killed in the siege of Thundera, including their king, Claudus.