In the mirror universe, Korvat was an unarmed Terran farming colony which was captured by the Klingon Empire in 2289. This was the first solid Klingon foothold into what had previously been inviolable Terran Empire space. It was located less than a lightyear from its border with the Klingons.
That year, the political and military elite of the Klingon Empire met on Korvat to celebrate. During a speech by General Kang, the Terran Empire's ambassador Curzon Dax arrived late and made no effort to remain inconspicuous. Within minutes, Curzon spat at Kang's feet in disgust and decried the manner in which the Klingons were celebrating the "least audacious victory in [their] history" and accused them of having a "miserable empire" before storming out, which earned him Kang's wrath. Having observed this incident, Regent Gorkon and his senior military adviser General Chang speculated as to whether this was a political stunt or whether Spock had chosen the young and inexperienced Dax in haste. Gorkon favoured the former explanation as he believed that the latter did not seem to be consistent with what he knew of Spock or Curzon's reputation. (TOS - Mirror Universe novel: The Sorrows of Empire)
By 2358, Korvat had become a Klingon-Cardassian Alliance mining colony. It was administered by Gul Zarale while the slave overseers included Glinn Broca and Kozak, who was eventually replaced by the former Terran slave Keiko Ishikawa in 2365. (DS9 - Mirror Universe short story: "A Terrible Beauty")