Second Excrothian Tetrarchy

The Second Excrothian Tetrarchy was a period of unparalleled scientific enlightenment on Excroth, and according to the Ninth Doctor, "the best rhubarb crumble this side of Wakefield". It should have been eons before the end of the planet's lifespan, but the planet was destroyed by this point when the Unon prevented the Excrothians from developing time travel by destroying the planet. (COMIC: Weapons of Past Destruction)