Eminiar VII was the inhabited seventh planet in the Eminiar system. It was the homeworld for the Eminians, a pre-warp-capable humanoid species. In the 23rd century, Eminiar VII was the principal planet of the NGC 321 star cluster. (TOS: "A Taste of Armageddon")
Prior to the late 18th century, the nation-states of this world united under the Eminian Union, an uniglobal government. The government was administered by the Eminian High Council from the capital city. The civilization was advanced, having had space flight for several hundred years, but it had elected not to venture outside of its star system.
Eminiar VII had been fighting a war with its colony, Vendikar the third planet in the system, 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. Every year, on Eminiar, one to three million were killed by this process. Legitimate targets in the war included vessels orbiting the planet, a fact that caused Kirk considerable difficulty during his visit. The reneging of this treaty by either side could result in a real war.
In 2267, the USS Enterprise visited this planet on a mission to open diplomatic relations with Eminiar VII. During the visit, when his ship and crew were threatened with the same fate as the Valiant, Captain James T. Kirk ended the war abruptly by destroying the computers that were conducting the simulated war. Ambassador Robert Fox began work with the two planets to create a lasting peace and to establishment of a Federation treaty port. (TOS: "A Taste of Armageddon")
In 2268, when held captive by the Kelvans, Captain Kirk asked Lieutenant Commander Spock if he could repeat what he did with the guard on Eminair VII by tricking him into believing the landing party had escaped. The attempt worked, but only briefly before the Kelvans recapture the landing party. (TOS: "By Any Other Name")
In 2375, a view of the surface of Eminiar VII was depicted on several viewscreens on Deep Space 9's Promenade and Replimat (DS9: "The Muse") advertising a trip to the "scenic Eminiar VII". (DS9: "What You Leave Behind")