(coexisting on another dimensional plane)
In the mirror universe, the Terran Resistance Forces were an armed group fighting the authority of the Klingon-Cardassian Alliance to obtain their freedom in what would be known as the Terran Rebellion. Though Terrans made up the majority of its ranks, other species such as Vulcans, Trills, and Ferengi were also involved.
The seeds of this group were formed on Terok Nor in 2370 when Benjamin Sisko was inspired by the prime universe Kira Nerys to rebel against the authority of Intendant Kira Nerys. Others, including Miles "Smiley" O'Brien also left the Alliance's influence for the Badlands where the Resistance was able to hide and plan further actions. One of these was the capture of Terok Nor from the Alliance as well as the capture of the Intendant, herself.
In 2375, upon the arrival of Quark and Rom from the prime universe, O'Brien stated that the cloaking device they had brought with them was now the property of the Resistance Forces, and would not be given to the Alliance as intended by the two Ferengi. (DS9: "The Emperor's New Cloak")