I came across alot of beautiful background paintings from Korgoth on William Wray's blog.(http://madaboutcartoons.blogspot.com) He so kindly posted this way back in 2006. Number 3 is from the scene when they're journeying to Specules's castle going around a bend on a mountain. Look at that Woolly Mammoth frozen in time! Love it!
The background was designed by Justin K. Thompson(http://squeakypen.blogspot.com/) and painted by William Wray.