The system consisted of a primary and at least five planets. Cardassia Prime (Cardassia II) was the inhabited homeworld of the Cardassians, a warp-capable species. This planet was also the capital of the Cardassian Union. (DS9: "Explorers") The system also included Cardassia I, and the planets Cardassia III, Cardassia IV, and Cardassia V that were colonized by the Cardassians. (DS9: "The Homecoming", "Shadowplay", "Prophet Motive")
In 2375, the Dominion began their withdrawal to Cardassia Prime during the waning days of the Dominion War. The Allied Forces planned a risky and costly military operation to end the war by penetrating the system and engaging the Dominion forces stationed in orbit over Cardassia Prime. (DS9: "The Dogs of War")
Background information Edit
"Tactical Display 7624N" was reproduced in legible detail in Star Trek: Star Charts (p. 49).
According to this same book (pp. 36, 42-43), the primary in the system was named Cardassia. Cardassia was a K class star with an absolute magnitude of -1.1, which was a hundred times brighter than Sol. There were a total of eight planets in the system, four of which were inhabited, and two asteroid belts. The system was visited by a Bajoran solar-sail vessel in 1571. Distance between Bajor and Cardassia was 5.25 light years.
According to the RPG book Star Trek: Deep Space Nine - Narrator's Toolkit, the Cardassian sun was a bright red dwarf (M2 V type), the first two planets were class F, Cardassia Prime was the third planet in the system, Cardassia VI and VII were class J gas giants and Cardassia VIII was class G.