The USS Enterprise encountered the Tholians in 2267 while investigating the loss of the USS Defiant in an interphase region. The Tholians demanded an explanation for the Starship's presence, and initially agreed to allow the Enterprise to remain in the area. When the ship was unable to provide proof of the Defiant's presence in the area the Tholians attacked the ship. The Enterprise proved militarily superior to the Tholian vessels, but was almost trapped within one of the forcefield webs, a system designed to enclose a vessel within a network virtually unbreakable strands.
In 2353 the Tholians attacked and nearly destroyed a Federation starbase, killing all but one of its complement. As recently as 2355 tensions remained high enough that Starfleet routinely trained against Tholian warships in simulations. Tensions remained sufficiently high that it was feared that they might become involved in the Klingon civil war, but eventually relations with the Federation were established and in 2371 a Tholian Ambassador visited Deep Space Nine. A Tholian observer was present at the ill fated Antwerp conference on Earth in 2372 when a bomb destroyed the conference hall. Tholian silk is highly prized as it is virtually frictionless.
