Benzar

[Benzar]] is a planet located in the Benzite system, and homeworld of the Benzite civilization – a significant member of the United Federation of Planets. Benzar's atmosphere differs somewhat from Class M norms, such as that before the 2370s Benzites offworld required a respiration device. (TNG: "Coming of Age"; DS9: "The Ship")

During the Dominion War, Benzar fell to the Dominion and Cardassian forces in 2374. However, the planet was later liberated by the Romulan Star Empire after it joined the war on the side of the Allies. Constable Odo expressed concerns that the Romulans would not give up control of Benzar even after the war ended, as their usual policy was to keep claimed territories. (DS9: "The Reckoning")

Apocrypha

In the early versions of the script, Bolarus IX was the planet conquered and reclaimed.

Based on the star charts seen as the Enterprise-E raced back to Federation space after their first encounter with the Scimitar it's likely that by this point Benzar has once again passed into Federation control, although this has yet to be confirmed in canon.