A once-famous road lies buried under grasslands, forgotten by the people of the areas it used to serve

When Xing Shangzhi, a farmer in his late 40s, herds his sheep and tends his potato plots along a hillside in Dazhaizi village, Fuxian, Shaanxi province, he often comes across rubble consisting of bricks and tiles that date back centuries. That fact is obvious from their shape and pattern, both of which are unusual today.

Like many local people, Xing and his wife live in a dwelling dug out of the hillside below the Ziwu Range. The ridge of the range, which runs from south to north in the western part of Shaanxi over a distance of about 413 kilometers, is unusually solid, making it ideal for the excavation of cave dwellings.

Other farmers and herdsmen living along the range in several counties often find similar treasures, including earthen pipes and ancient coins of various shapes.

If that was not enough, unlike other local mountain ranges, whose ridges are often shaded by thick woodland, the ridge of the Ziwu Range is either covered by short grasses or is bare, making it look like a 10-to-60-meter-wide belt meandering along the length of the range.

For generations, the ridge has not only served as an ideal roof for cave dwellings, but also as a natural dirt road; sturdy and reliable.

Although the Ziwu Range is in the center of the Loess Plateau - an area the size of France, covered with layers of fertile soil dozens of meters deep blown from deserts in the north and west over millions of years - the soil of the ridge seems light and flimsy, meaning large plants are unable to lay deep roots.

That flimsiness is the result of an intermediate layer of extremely compact earth, about 1 or 2 meters thick, which is a lighter color than the yellow earth in which it is sandwiched.

It is in this soil layer that farmers unearth the rubble that can only have belonged to urban dwellers, and the strong layer below it, usually mixed with gravel, serves as a roadbed for the dirt path that follows the ridge of the Ziwu Range.