The Kohn-Ma was a Bajoran group that fought against the Cardassians during the Occupation of Bajor, and continued terrorist activities against Cardassians after their withdrawal from Bajor. They also carried out terrorist acts against Bajorans who they disagreed with politically, including the assassination of a Bajoran minister in 2369.
The Kohn-Ma was one of the groups opposed to the Federation presence in the Bajoran system. When the Bajoran wormhole was discovered, Kohn-Ma operative Tahna Los decided to collapse the entrance to the wormhole by using an explosive device. The crew of Deep Space 9 foiled this plot, and Tahna was taken into custody. (DS9 episode: "Past Prologue")
In 2370, there were a series of bombings aboard Deep Space 9. At the scene of the second bombing, Garak's shop, there was a poster that read "Die Cardassians!" on the wall. It was signed, Kohn Ma. There were other posters of anti-alien sentiment found at other bombings, all signed by Kohn Ma. It was later revealed that the Bajoran monk Leiris, who was working for the Cardassians, placed the bombs. (DS9 novel: Betrayal)
In an alternate timeline, Jennifer Sisko was killed in an attack by the Kohn-Ma on Cardassia Prime when Benjamin Sisko was there negotiating on behalf of the Federation Diplomatic Corps for a Cardassian withdrawal from Bajor. (DS9 novel: Fearful Symmetry)