Wiktionary
back forty
n. 1 (label en US) The remote part of a farm. 2 (label en US idiomatic) The most remote or inaccessible part of any place.
Usage examples of "back forty".
Matthew's Elementary School in northeast Baltimore back forty-plus years earlier&mdash.
I've had such good luck nearly all my life, and for the year I lost have been given back forty.
You go back forty millenniums in human history and what do you have?
His square, brown-skinned face reflected a solid career that went back forty-five years.
Comes back forty minutes later, lands, gets back into his car, and burns rubber out of there.
They are an ancient species, with a recorded history going back forty billion years.