In the five hundred years leading up to 4000, the Daleks conquered the Second, Third and Ninth Galaxies in a war across the Outer Galaxies. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)
One account indicated that Skaro history was relative to the "second galaxy calendar", whose name could be read to mean the calendar of the "second galaxy". (PROSE: Davros: Genius or Madman? [+]Loading...["Davros: Genius or Madman? (feature)"])