The Kyrian and Vaskan homeworld was a planet in the Delta Quadrant, inhabited by two humanoid species, the Kyrians and the Vaskans, who held divergent cultures and traditions.
24th century[]
In 2374, the situation between Kyrians and Vaskans was tense. According to the Vaskans, the Kyrians had been threatening to attack and war might break out any day. In this period, USS Voyager visited the planet and reached an agreement with Ambassador Daleth to trade medical supplies to the Vaskans in exchange for dilithium.
Just as these talks were concluded, three ships attacked Voyager and a Kyrian team managed to board the ship. The leader of the raid, Tedran, believed that Voyager was instead negotiating an alliance with the Vaskans, and that the ship was about to attack the Kyrians. A goal of the raid was to capture technology. As the Kyrian team was neutralized, Daleth to the horror of Captain Kathryn Janeway killed a surrendering Tedran. Three of Voyager's crew were also killed in the incident.
At some later point, speculated to be during a subsequent attack with more ships, the EMH backup module was removed from the ship. It ended up buried nine meters beneath the ruins at Kesef.
Shortly after, the Great War broke out between the Kyrians and the Vaskans. A revisionist version of history would later record eight million killed by biogenic weapons provided by Voyager, and how the war left the Kyrian Dynasty in ruins. Tedran was rehabilitated as a man of wisdom and peace, while the Voyager crew came to be portrayed as vicious war criminals. Among other things, Janeway, far from being horrified at Tedran's death, was believed to have killed Tedran herself. (VOY: "Living Witness")
31st century[]
By the 31st century, seven hundred years after this conflict, the consequences of the war were still felt. Kyrians and Vaskans lived together in relative peace, but a Kyrian struggle for equality was still ongoing. Kyrians were forced to live outside of city centers, and their children could not attend the same academies as those of Vaskans. Overall, the Vaskans were more powerful, though the Kyrians were very angry.
During this period, artificial lifeforms were considered sentient and responsible for their actions on this planet. If found guilty of serious crimes, their programs could be decompiled. Holotechnology existed on the planet, but was different from that familiar to Starfleet. Photon grenades were another available technology. (VOY: "Living Witness")
Revisionist history of the Great War[]
By the 31st century, Kyrians and Vaskans differed in their view of the war: the Vaskans had always believed that the Kyrians were the aggressors, while the Kyrians characterized the war as a conspiracy to oppress the Kyrians. Some Vaskans believed that the Kyrians used their history of subservience as an excuse to blame all their problems on the Vaskans.
Note that despite all that's learned in the episode, neither the Kyrian and Vaskan analysis are not necessarily right or even contradictory: while the backup Doctor's simulation appears to show the Kyrians as attacking first, the Doctor denied knowing who started the war, and Daleth described the Kyrians with a disdain that betrays a deep pre-existing animosity on his side.
A revisionist history of the events leading up to the war was propagated. The Museum of Kyrian Heritage featured an exhibition called The Voyager Encounter, which portrayed the Voyager crew as savage while the Kyrians were portrayed as martyrs and heroes.
However, this changed as a backup copy of The Doctor was discovered buried under the ruins at Kesef. With the help of Quarren, curator of the Museum of Kyrian Heritage, he corrected the inaccurate reconstructions of Voyager's visit. However, the revelations also caused racial tensions that had been building for some time to spill over in a race riot. Still, in less then six years after the revelations, the dawn of harmony had come. (VOY: "Living Witness")
The Star Trek: Star Charts (p. 89), identifies this planet as Vaskan-Kyrian. It orbited a class A star. The Voyager visited this planet on stardate 51850.