OK, fine, BUT WHERE?

You can say that the Realms is old, I know that.

But on what page of the source material does it actually first appear?

That's what I'm looking for here. I've looked through the boxes I have and it simply isn't there as best I can tell (I may simply be missing it, I admit it).

I'm looking, literally, for a page reference if somebody can get it to me.

Honestly, the first time I remember hearing about it was in the 3.x days.