The Breen Confederacy was the official government of the Breen species. This confederacy was located in the Alpha Quadrant. In late 2375, the Breen Confederacy entered the Dominion War, allowing itself to be annexed by the Dominion as the Cardassian Union had been two years prior.
According to the terms of the annexation, the Breen Confederacy received several planets from the Cardassian Union as compensation for joining the war. The Breen would also be given control of the Romulan Star Empire in the post-war galaxy. The Founders also promised the Breen control of Earth, though Weyoun was also given this assurance. The union was negotiated between the Female Changeling and Thot Gor, a prominent official in the Confederacy.