Dragonia Kingdom

The Dragonia Kingdom is the antagonist group in God Mazinger. Originally forced underground years ago, they plan to take over Mu and gain its hidden treasure the Koshurishimono. Led by Dorado until his death with his son Eldo taking over. They have advanced technology able to build or reconfigure robots called the Megalo Legion as well as witchcraft to defeat enemies.

Manga
In the manga, the Kingdom has a different origin. Originally they were aliens from a world called Dora that was ruined by the biomechanical weapons, the Megalo Legion. The inhabitants had went out into space to find a new world to inhabitant. Eventually they found Earth but were only able to adapt to living in the conditions on the edge of the continent of Mu. Using their advanced technology, they managed to reconfigure their physiologies to better suit the rest of the continent and take it from the Mu people by force through war and use revived dinosaurs as war animals. The main reason was because Mu possessed a special device called the Hidden Elm which could manipulate genes and fix the quickly decaying cells of the royal family.

Dorado had lead his Kingdom to conquer Mu and take the Hidden Elm to restore his dying family. His son Eldo, had planned to overthrow his father and take a more offensive approach to conquering Mu such as using nuclear weaponry, genetic experiments, and even the Megalo Legion which destroyed Dora in the first place. At the end, the kingdom is wiped out by the God Mazinger as it caused Earthquakes which decimated the armies and eliminated the entire royal family.

Trivia

 * The Dragonia Kingdom have a counterpart in Getter Robo, the villainous group the Dinosaur Empire.