A corduroy road<span> or </span>log road<span> is a type of </span>road made by placing logs<span>, perpendicular to the direction of the </span>road<span> over a low or swampy area. The result is an improvement over impassable mud or dirt </span>roads<span>, yet rough in the best of conditions and a hazard to horses due to shifting loose </span>logs<span>.</span>
I believe your answer to this is the Nubian civilization.
