'Backside' in the Bible

Now Moses kept the flock of Jethro his father in law, the priest of Midian: and he led the flock to the backside of the desert, and came to the mountain of God, even to Horeb.

And the remnant that remaineth of the curtains of the tent, the half curtain that remaineth, shall hang over the backside of the tabernacle.

And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals.