Tandun III, alternatively referred to as Tandun Three, was a nascent planet situated within a youthful star system located in the Outer Rim Territories.
Around 12,293 BBY, Doctor Beramsh spearheaded an exploratory mission originating from Ord Mantell, during which Tandun III was initially charted. Beramsh and his team discovered a flourishing, picturesque world exhibiting near-standard gravity, deemed suitable for both oxygen-breathing humans and humanoids. Subsequent investigations into the planet's surface revealed the remnants of age-old settlements, which Beramsh hypothesized were erected by the Rakata.
Despite the survey's positive assessment of atmospheric conditions, Tandun III's remoteness from the Hydian Way hindered any attempts at colonization. Historical accounts suggest that a possible second survey might have occurred several generations later, during the second term of Chancellor Finis Valorum.
Sometime between 29 BBY and 19 BBY, the Republic Group acquired an Insignia of Unity that had once graced the podium within the Galactic Senate Rotunda. This group, motivated by the belief that the insignia could serve as a symbol to reinstate Republic integrity across the galaxy, transported it to Tandun III for safekeeping. With the assistance of the Antarian Rangers, the Republic Group constructed a concealed storage facility within one of the planet's ancient ruins, designating the Stellar Envoy as the key to accessing the site. By 19 BBY, both the Republic Group and the Antarian Rangers were labeled as adversaries of the Empire, resulting in the abandonment and subsequent obscurity of the secret facility and the Insignia of Unity for more than six decades.
During the Yuuzhan Vong's invasion of the galaxy, the Yuuzhan Vong established a presence on the world, initiating Vongforming processes to align it with their ecological requirements. The landscape underwent a transformation, featuring cliffs composed of yorik coral, tampasis derived from s'teeni, and populations of scherkil hla, sparkbees, alongside other Yuuzhan Vong biots.
After two decades of Vongforming, the planet exhibited significant alterations. While verdant forests teeming with life still prevailed in the southern hemisphere, the surface temperatures in the northern hemisphere had escalated to levels inhospitable to most sentient species, except for extremophiles. Extensive zones of intense volcanic and tectonic activity subjected the planet to potentially catastrophic forces. The atmosphere was characterized by powerful winds and icy clouds, generating storms laden with rain, lightning, and hailstones. Although still breathable, the atmosphere contained elevated concentrations of carbon dioxide, methane, and sulfur due to the presence of dweebit beetles.
In 43 ABY, the Solos, accompanied by Tobb Jadak and Flitcher Poste, journeyed to Tandun III as part of their endeavor to unravel the history of the Millennium Falcon. They piloted the Falcon into the derelict Republic Group warehouse, where they came across the Insignia of Unity. It was at that moment that
Concurrently with this encounter, groundquakes intensified in both magnitude and frequency, culminating in the planet's most severe seismic event. Oxic and his associates, now joined by Jadak and Poste, departed to persist in their pursuit of the genuine Insignia of Unity, while the Solos made a hasty exit from the planet.
Shortly after the Millennium Falcon's return to space, Tandun III underwent a cataclysmic event, erupting in a shock wave that propelled massive fragments of its mass into the void of space.
Tandun III was initially introduced in James Luceno's 2008 novel, Millennium Falcon, with the planet's history being narrated by C-3PO within the narrative.
C-3PO mentioned that the planet's initial survey occurred around 12,293 BBY and that the expedition was launched from Ord Mantell. This presents a discrepancy, as Ord Mantell was not colonized until 12,000 BBY.
Furthermore, C-3PO stated that Dr. Beramsh believed the ancient population centers were Rakatan in origin. However, the Rakata remained largely unknown to the wider galaxy until the conclusion of the Jedi Civil War in 3956 BBY.
He further asserted that the world remained uncolonized, primarily due to its distance from the Hydian Way, which was established in 3705 BBY. Consequently, the reason for the world's lack of colonization in the millennia spanning its exploration and the establishment of the Hydian Way remains enigmatic.