Tholian Assembly
The Tholian Assembly was the xenophobic interstellar government of the Tholian species. The territory of the Assembly included the region of space known as the Tholian sector. () This was an Alpha Quadrant power. ()

Location 

The border to the space annexed by the Tholian Assembly was located in free space that had not yet been surveyed by the  in 2268. () 

In 2293, the location of the Tholian Assembly in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the . (, okudagram)

According to K'Ehleyr, in 2367, wars fought by the Klingon Empire tended to drag in the neighboring star systems, the Tholian Assembly, the Ferengi Alliance and eventually the Federation into the fighting. ()

History 
By 2152, the Vulcan High Command had only limited contact with the Assembly. When s traveled far beyond their territory to salvage a 31st century , it was discovered that the Assembly may have been a faction in the Temporal Cold War. ()

In 2268, the  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  attempted unsuccessfully to rescue the Defiant from the spatial interphase. (; )

The 2350s saw an increase in hostilities between the Assembly and the Federation. In 2353, the Tholians destroyed a Federation starbase. () Starfleet developed Tholian-based battle simulations. In 2355, during one such simulation, William T. Riker used a notable strategy to calculate a sensory blind spot on a Tholian vessel. ()

In 2372, one ambassador was acquainted with Benjamin Sisko of Deep Space 9, to whom he owed a favor. () In 2372, a Tholian observer was killed in a bombing on Earth by a Dominion infiltrator. () In 2373, the Tholian Assembly signed a nonaggression pact with the Dominion, and remained neutral during the Dominion War. Odo considered this to be an impressive inroad into the Alpha Quadrant for the Dominion. () In 2379, there was a Tholian ambassador on Romulus. ()

Appendices

Background information 
"Tholia" was a word – possibly a proper noun – that Klaang mentioned in the  episode , but which Hoshi Sato could not translate. 

According to Star Trek: Star Charts (pp. 35 & 37, "United Federation of Planets II") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385), Tholia was the capital planet of the Tholian Assembly. Federation scientists theorized that Tholia was a Y-class planet. The dominant species on Tholia were the non-humanoid Tholians. Diplomatic relations were established with the Federation in 2271. The primary Tholia was a B-class star.

Apocrypha 
According to The Worlds of the Federation (p. 150), Tholia was in fact the home planet of the Tholians.

In the alternate reality  "The Tholian Webs, Part 2", Commander Loskene accuses the  of crimes against the Tholian Assembly, the ship having inadvertently intruded on Tholian space. Loskene plans to tow the craft back to the Tholian homeworld to answer for those deeds. However, once the Enterprise manages to escape, Loskene threatens the ship's crew with "the wrath of the Tholian Assembly" and warns that war will follow, the next time their civilizations meet.

External links 
 
 

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Governments