The Bajoran-Cardassian Treaty was an historic peace treaty between Bajor and the Cardassian Union signed in 2371. Vedek Bareil was the chief Bajoran negotiator for the treaty, while Legate Turrel represented the Cardassian Union. Although Bareil was injured and close to death, he helped Winn Adami to finish the negotiations. The signing of the Treaty sent shock waves throughout the Alpha Quadrant. (DS9: "Life Support")
Even with the new treaty, the Bajorans were still suspicious of the Cardassians and upgraded the orbital sensor platforms at Prophet's Landing, the closest Bajoran colony to Cardassian space. (DS9: "Heart of Stone")
The Obsidian Order was strongly opposed to the Treaty and sent an operative, Dejar, to sabotage a combined Federation-Bajoran-Cardassian effort to place a subspace relay station in the Gamma Quadrant. The Vedek Assembly as a whole endorsed the treaty, though at least one individual Vedek, Yarka, opposed it and was defrocked for his opposition. (DS9: "Destiny")
In a message Enabran Tain sent to the Cardassian government, he mentioned the treaty, alongside the Federation-Cardassian Treaty, as the factors that blinded the Cardassian government to the danger of the Dominion. (DS9: "The Die is Cast")
In "Call to Arms", Dukat makes no mention of this treaty, which could mean that the Union seceded from it, upon joining the Dominion. However, the Bajoran-Dominion nonaggression pact seems to have served the purpose of maintaining peace between Cardassia and Bajor.
In the original version of DS9 Season 3's "Life Support", the political issues which, later in the development of the episode, became the Bajoran-Cardassian Treaty were peace negotiations between the Federation and the Romulan Star Empire, as well as the elimination of the Romulan Neutral Zone. (Cinefantastique, Vol. 27, No. 4/5, p. 106)
When peace with the Romulans was deemed too inconsequential for Star Trek: Deep Space Nine and insufficiently compelling, the Cardassians and Bajorans instead became the two negotiating parties. Commented Ronald D. Moore, "It became more of a Deep Space Nine story. Suddenly we had some real stakes." Also, whereas the original form of the story had the peace negotiations happening all off-camera, this was evidently changed too. (Star Trek: Deep Space Nine Companion, pp. 205 & 204)
The fact that the Bajoran-Cardassian Treaty had been established on DS9 prior to the writing of third season installment "Destiny" allowed the series' writing staff to include it in that outing. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 92)
Ron Moore wanted to structure the events of the season three episode "Explorers" around the treaty. In fact, in a developmental memo written by Moore shortly before René Echevarria scripted the installment, Moore suggested the notion, saying, "Let's tie it in to the treaty that was established in 'Life Support'." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 96) However, the treaty isn't directly mentioned in "Explorers".