- "Wesa have little favor to ask you. We wanta new Gungan city on the empty moon. But there's no life there. Nottin to build with, nottin to eat."
- ―Boss Nass, to Amidala and Kenobi
The colonization of the water moon Ohma-D'un in 32 BBY was the result of a joint effort between the Gungans and the Human inhabitants of Naboo. The Gungan Boss Nass, initiator of the project, enlisted the help of his new allies, Queen Amidala and Obi-Wan Kenobi to bring the plants and creatures destined to populate the empty moon. While the mission was successful and led to the establishment of New Otoh Gunga, a majority of the colony was destroyed about ten years later when the Confederacy of Independent Systems used its poisonous swamp gas on the Gungans during the Battle of Ohma-D'un.
- "Yousa no tinken yousa greater den da Gungans… Mesa like dis. Maybe wesa bein friends."
- ―Boss Nass to Queen Amidala
In 32 BBY, the two sapient species that called Naboo their homeworld had forged an alliance after millennia of mutual mistrust: the Humans and Gungans had united their forces to reclaim their planet, which had been subjugated by the Trade Federation. In the ensuing period of prosperity and collaboration, the Gungan Boss Rugor Nass changed his long-standing policy of seclusion, opened the underwater capital of Otoh Gunga to offworld visitors. Because of that, the city gained more and more inhabitants, until it became threatened by overpopulation. Intent on preserving the ecological balance of Lake Paonga, in which the capital was located, and of the surrounding wilderness, Nass decided to establish a new colony on the water moon Ohma-D'un, the largest of the three natural satellites in orbit around Naboo.
- "Wanna yousa bring da plants and animals in the big bongo ship? Yousa release the right critters so that the moon bombad busy with life! Then wesa come to the moon."
- ―Boss Nass, to Amidala and Kenobi
To help him handle that critical mission, Boss Nass turned to his new ally, Padmé Amidala, Queen of the Naboo. Under the guidance of Graf Zapalo, chief science advisor to Amidala, Gungan scientists and Naboo starship engineers worked together to come up with a number of new technologies. The crowning achievement of that collaboration was the Mantaris-class amphibious medium transport, a spaceworthy version of the traditional Gungan bongo submersible. In the mean time, the Gungans collected creatures and plants from Naboo and many other worlds such as Endor, Alderaan and Tatooine, hoping they would thrive on the empty water moon.
Before the arrival of the Gungan colonists, the Gungan High Council asked Queen Amidala to travel to Ohma-D'un in the company of the Jedi Knight Obi-Wan Kenobi, the Gungan Bombad General Jar Jar Binks and the astromech droid R2-D2. Together, they were to discover how the animals and plants they intended to introduce on the moon's surface would interact and how they would depend on each other to live. Once they obtained an ecologically sound environment, the Gungan settlers started to harvest valuable resources and use them to build the New Otoh Gunga. The physician Portillo, a citizen named Josie, a male librarian and the smuggler Toba were among the first settlers.
At some point during the colonization process, a shipment of machine parts was to transit from Oxon City to Ohma-D'un, but ultimately got hijacked by pirates before it could reach the moon installation. A group of heroes was subsequently assigned to escort all future shipments. After conducting a number of uneventful escorts, the heroes ended up facing another raid. With the help of one of the pirate fighters, who suddenly changed sides, the escort managed to take the pirate leader captive, forcing the entire group's surrender.
- "The Confederacy has turned Ohma-D'un into a graveyard…"
- ―Anakin Skywalker
Although the colonization effort was successful, the new Gungan moon did not enjoy its newfound propserity for long. In 21.8 BBY, while the Clone Wars were being fought throughout the galaxy, Ohma-D'un was the scene of a battle bewteen the forces of the Galactic Republic and of the Confederacy of Independent Systems. While the Republic emerged victorious from that battle, the Gungan colony had been decimated by the Confederacy's deadly swamp gas.
- Star Wars: Yoda's Challenge Activity Center (Mentioned only)
- Star Wars Episode I: The Gungan Frontier (First appearance)
- Peril in the Ionosphere"—Star Wars Gamer 1 (Mentioned only) "