Zabol
زابل
Rostam's country, out at the eastern edge of everything.
Zabol, or Zabolestan, is the east: the far side of the empire, where Zal's house holds land the crown does not really govern and cannot do without. Rostam is from there, and the distance matters.
Everything he does, he does as an outsider who was sent for. He arrives, fixes it, disagrees with the king in front of the whole court, and goes home east. When the poem calls him the man from Zabol it is not being geographical. It is describing a position: the person the centre leans on and does not control.
In the game
Zabol's name turns up on something in the game that is about taking a chance instead of playing it safe. Which is in character.