Ah, I think I can give a sort of answer to that as well - it's best if there is no one and only place where they come from, due to additive worldbuilding. Or in other words, anything goes as long as it doesn't restrict others.
*offers an applepie*
"First, I will not permit the spreading of other religions in this place."
"This means no dubious forbidden magic rituals on the mountain grounds."
I suppose Till won't be able to visit after the D rank exam xD