Vendikar (or Eminiar III) was an inhabited planet. This was the homeworld of the Vendikans, a pre-warp capable humanoid species. It was the third planet in the Eminiar planetary system. This system was located in NGC 321, (TOS: "A Taste of Armageddon") a star cluster of the Alpha Quadrant. Star Trek VI: The Undiscovered Country, production art)
Vendikans were the descendants of colonists from the planet Eminiar VII who settled this world in the distant past. Prior to the late 18th century, the nation-states of this world united under an uniglobal government. The government was administered by the Vendikar High Council from an unnamed capital city. The civilization was advanced, having had space flight for several hundred years, but it had elected not to venture outside of its solar system.
Vendikar had been fighting a war with the principal planet in the system, Eminiar VII, for five hundred years. The conditions of this war were stipulated in a treaty signed by both worlds. This was a simulated war with causalities determined by computer projections, and the people willingly killing themselves in disintegration stations. Legitimate targets in the war included vessels orbiting the planet. The reneging of this treaty by either side could result in a real war.
In 2267, the USS Enterprise visited the planet Eminiar VII. During the visit, when his ship and crew were threatened with destruction, Captain James T. Kirk ended the war abruptly by destroying the computers. Ambassador Robert Fox began work with the two planets to establish a lasting peace. (TOS: "A Taste of Armageddon")