The Eye of Zeitoon by Talbot Mundy (World's Classics)

The gut of the pass rose toward Zeitoon at a sharp incline--a ramp of slippery wet clay, half a mile long, reaching across from buttress to buttress of the impregnable hills. It was more than a ridden mule could do to keep its feet on the slope, and we had to dismount. It was almost as much as we ourselves could do to make progress with the aid of sticks, and we knew at last what Kagig had meant by his boast that nothing on wheels could approach his mountain home.