Tholian Assembly

The Tholian Assembly is the government, and military of the Tholians. It is run by a High Magistrate.

The Tholians first encountered a Human vessel, Enterprise in 2152. (ENT episode: "Future Tense")

In 2268, the Tholian Assembly ordered the destruction of a Klingon colony on Taelus II. The USS Defiant (NCC-1764) was carrying proof of this back to the Federation, when it received a distress call from a interphasic rift, and disappeared shortly after the USS Enterprise (NCC-1701) arrived to assist.

After the first contact in many years between the Tholian Assembly and the Federation, the two opened official diplomatic ties in 2271. (Star Trek: Star Charts)

However, those ties were minimal at best. The Tholians rarely contacted the Federation, however they did slow their expansion, and ceased expanding in Federation territory. Better Tholian relations between the Assembly and the Federation opened in 2298, after a peace conference. (TLY novel: "The Sundered")

In 2376, the Defiant reappeared. The USS da Vinci was sent to retrieve it, and several Tholian starships oversaw it. However, when proof that they had performed the massacre at Taelus was discovered, the Tholian Assembly ordered the destruction of the da Vinci. They were fought off and forced to retreat however, by the joint powers of the da Vinci and the Defiant. (SCE novels: "Have Tech, Will Travel", "Miracle Workers")

The Tholian Assembly signed a non-aggression pact with the Dominion in 2373, and did not get involved through out the Dominion War. (DS9 episode: "Call to Arms")