Fact: The Vulcans have been a space faring race for a million years.
Fact: The Vulcans mentored humanity in all things space.
Supposition: the Border between the Alpha and beta Quadrants runs through Vulcan.
fact: Vulcan was destroyed in the 2009 movie.
Extrapolation: The border to the Alpha beta Quadrant moved to the next most important world in the Federation.
Question: Is that Earth?