The people within the Earth are supposed to be small, with Alaskan like features. Not much variation within the race. they say they live in peace and do not get ill. So they do not want to come to the earth's crust where we have wars and cannot understand the basic premis of peaceful thinking/living.
I read this in a book called Agharta. Not to be confused with the channeled work Agartha by meredith young. It was actually a softbound paper written by a doctor in 1950. I came across it at an old book sale.
I wish I could send you a copy Karlin!! You would be able to figure it out better than I can.
I have to go look for it, I havent read it in a while...