The Guidon Space Pontificate, or Guidon Pontificate, was the Guidon member state in the United Federation of Planets by the 2360s. (TNG - The Sky's the Limit short story: "Meet with Triumph and Disaster")
In an alternate timeline were the Vulcans remained a violent and emotional species, the Guidon Space Pontificate was a supermassive interstellar state in the Beta Quadrant that bordered the Klingon Empire.
In 2293, the Interstellar Union intelligence service found out that the Klingon Empire had acquired non-aggression treaties with the Gorn Hegemony, the Guidon Pontificate, and the Holy Order of the Kinshaya. (ST - Myriad Universes novel: The Tears of Eridanus)