Following the death of Treuten by Admiral Natasi Daala, Kosh took control and continued to rule over the Federated Teradoc Union, however he did not go with Vice Admiral Gilad Pellaeon and the remnants of the Empire to establish a "Imperial Remnant" on the very edges of the galaxy. However, the Federated Teradoc Union finally fell after Kosh was assassinated by New Republic operatives on Ryvester in 13 ABY.
After the Imperial defeat at Endor in 4 ABY, the Imperial Navy officers Kosh and Treuten Teradoc established themselves as independent warlords, with Kosh forging an in the Deep Core, while his brother Treuten oversaw the establishment of the Greater Maldrood, a series of territories in the Mid Rim. Though the two territories initially operated independently of one another, in 8 ABY Treuten was forced to call upon his brother for help after he became targeted by both Imperial and New Republic forces, and when Kosh successfully defended Treuten's holdings, the two siblings combined their territories to form the "Federated Teradoc Union."
The two Teradoc brothers continued to enlarge their empire, by expanding their borders toward each others territories, though their alliance was almost shattered after the pirate Leonia Tavira attempted to cause a rift in their relationship. Following the reemergence of the Emperor Palpatine—who had survived his death at Endor by possessing a clone body—in 11 ABY, the Teradocs pledged their combined forces to Palpatine's Dark Empire. Palpatine's campaign was a failure and Treuten's fleet was left severely battered, and in the aftermath of the Palpatine restoration, Kosh ordered Treuten to retreat to the Deep Core with his fleet whilst Kosh attempted to defend their Mid Rim holdings in the Greater Maldrood.
In an attempt to prove his worth to his brother, Treuten launched a new campaign against the Teradoc Union's primary rival in the Deep Core, the Zero Command of Lord High Admiral Blitzer Harrsk, with Vice Admiral Gilad Pellaeon leading Treuten's fleet of Victory-class Star Destroyers. After Teradoc staged a raid on Harrsk's fleet, Harrsk retaliated and attacked Teradoc's own forces in the Hakassi system, though the battle was brought to a stalemate by the actions of Admiral Natasi Daala.
After Daala subsequently failed to negotiate an alliance between Treuten and 12 other influential Deep Core warlords at Tsoss Beacon, Daala executed Teradoc and all of the other warlords present, then seized control of their holdings to form a united Imperial force after talks on Imperial Reunification failed, leading to Kosh falling from grace while under the guise of Daala, the Federated Teradoc Union forces passed to Vice Admiral Gilad Pellaeon who joined the United Warlord Fleets. However after the failed assault on Yavin 4, Daala relinquished full command to Pellaeon who left the Federated Teradoc Union and formed the Imperial Remnant.
Despite the loss of his brother and their Deep Core holdings, Kosh took control and continued to rule over what remained of the Federated Teradoc Union and was not a party to Pellaeon's Imperial Remnant. However, the Teradoc Union finally crumbled after Kosh was assassinated by New Republic Intelligence operatives on Ryvester in 13 ABY.
- The Official Star Wars Fact File125