Prior to the Clone Wars, New Plympto was welcomed into the Galactic Republic as a source of rikknit eggs, the Nosaurians' chief export. However, they were denied representation in the Galactic Senate and eventually grew alienated. Soon enough, the market for rikknit eggs evaporated and New Plympto was, for all intents and purposes, abandoned by commercial interests.
With the outbreak of the Clone Wars, the Confederacy of Independent Systems recruited New Plympto to their cause with the promise of reviving the rikknit egg market and rebuilding the planet's economy. Jedi Master Dass Jennir led a battalion of clone troopers on New Plympto against the Nosaurian rebels but Jennir sought refuge with the Nosaurians after his clone troops received Order 66. The Hajial Chase, an old stretch of forest 400 km from Phemiss and surrounding woodlands served as shelter to renegade Nosuarians.
Following the Clone Wars, New Plympto begrudgingly became an Imperial world. The resistance was quickly and easily quashed by the Nosaurians' new Imperial masters. An Imperial governor ruled the planet from a facility on Karsten Moon, where corporate scientists conducted experiments to synthesize the drug called ji rikknit from a few captive rikknit species, though their best result was an inferior narcotic with harmful side effects.
The planet continued to be under Imperial control until the defeat of the Empire and the rise of the New Republic.
Before the Yuuzhan Vong took control of the planet, it had a population of about fifteen million living on its surface. When the Yuuzhan Vong attacked, a resistance movement under Numa Rar was formed. The Yuuzhan Vong grew tired of the fierce resistance on the planet and used a biological weapon on New Plympto, killing seven million on the surface. The planet was rendered uninhabitable.