A Tholian
A Federation star chart depicting the location of the Tholian Assembly
The Tholian Assembly was the government of the race of xenophobic non-humanoid beings known as Tholians. The Assembly inhabited a region of space bordering the Federation and the Klingon Empire. (TOS: "The Tholian Web"; TNG: "Reunion") The location of the Tholian Assembly was depicted on a Federation star chart in 2293. The Assembly was located near Gamma Canaris N, Berengaria VII and Janus VI. (Star Trek VI: The Undiscovered Country)
History
By 2152, the Vulcan High Command had had only limited contact with the Assembly. When Tholian ships traveled far beyond their territory to salvage a 31st century time-travel pod, it was discovered that the Assembly may have been a faction in the Temporal Cold War. (ENT: "Future Tense")
In 2268, the USS Defiant entered a region of space annexed by the Tholian Assembly in response to a fake distress call sent by mirror universe Tholians through an interphase. Three weeks later, the starship USS Enterprise attempted unsuccessfully to rescue the Defiant from the spatial interphase. (TOS: "The Tholian Web"; ENT: "In a Mirror, Darkly")
The 2350s saw an increase in hostilities between the Assembly and the Federation. In 2353, the Tholians destroyed a Federation starbase. (TNG: "The Icarus Factor") Starfleet developed Tholian-based battle simulations. In 2355, during one such simulation, William Riker used a notable strategy to calculate a sensory blind spot on a Tholian vessel. (TNG: "Peak Performance")
In 2371, a Tholian ambassador visited Deep Space 9. (DS9: "Defiant") In 2372, a Tholian observer was killed in a bombing on Earth by a Dominion infiltrator. (DS9: "Homefront") In 2373, the Tholian Assembly signed a nonaggression pact with the Dominion, and remained neutral during the Dominion War. (DS9: "Call to Arms") In 2379, there was a Tholian ambassador on Romulus. (Star Trek Nemesis)
Background
According to Star Trek: Star Charts, on pages 35, the capital of the Tholian Assembly was Tholia. The planet Tholia was a Class Y planet that orbited a blue giant in the Alpha Quadrant, as shown on page 37.
Tholia was a word that Klaang mentioned in the Star Trek: Enterprise episode "Broken Bow", but which Hoshi Sato could not translate.
Apocrypha
According to The Worlds of the Federation (page 150), Tholia was the home planet of the Tholians.