The Intergalactic Conference of Andromeda was held some time prior to the year 4000. Zephon implied that Mavic Chen, the Guardian of the Solar System, had sponsored it as well as attending the conference.
At the same time, representatives of the Outer Galaxies had conferred with the Daleks and sent along one delegate, Trantis, so as to not arouse any suspicions. (TV: The Daleks' Master Plan) Sentreal had meant to go to the conference, but he ended up at the Galactic Council meeting, only realising at its end the conference he meant to go to would likely have occurred on Andromeda. (PROSE: Sentreal)