The Founders are a group of Changelings who reside in the Gamma Quadrant. They founded and rule the Dominion in the guise of gods to the Jem'Hadar and the Vorta. (DS9 episodes: "The Jem'Hadar", "The Search, Part I", "The Search, Part II")
The Founders did not possess a concept of ally or treaties. In their mind, there was only a master or a slave; if one was not a master, one was a slave.
During their scouting of the Alpha Quadrant in their attempt to bring order to that region of space, the Founders showed an interest in the Klingon Empire. They saw the Klingon warrior society as the Alpha Quadrant's equivalent of the Jem'Hadar and, thus, the best material to be converted into servants in the Dominion. (DS9 novel: Vengeance)