Judea and Jerusalem is allegory of Judea and Jerusalem (!). Specific territory in opposition to generic territory ("Galilee").
The same dichotomy between named people in Mark and not-named people in Mark.
Galilea is anonymous land insofar it is allegory of the Roman Empire.
Now, if Mark is based on Paul, where did Mark take the idea that Jesus had to appear the first time in Galilee?
Best answer: in Galatians 1:15
The first place, the more pure and spiritual place where Jesus appeared ON THIS EARTH was INSIDE Paul.But when God, who set me apart from my mother’s womb and called me by his grace, was pleased 16 to reveal his Son in me so that I might preach him among the Gentiles, my immediate response was not to consult any human being.
How could the Galilee be allegory of what is IN the man called Paul?
The best answer is that this allegory (Galilee=what is IN Paul) may work only if we identify the free spirituality (of the mystical people who "saw" Jesus, like Paul) with the territory not circumscribed by the specific features of the traditional places of meeting of the deity. Galilee is all and nothing, from this prospective. Jesus is everywhere in the Roman Empire and nowhere in the Roman Empire (because he is hidden in Paul).
But then Mark is proclaiming a God who did sanctify not more a mere temple, but the entire world.