site of the old stone age

age ancient asia barrier beijing blue brick cave china chuan colossal culture curve desert dynasty eastern famous fortification gou gray great gully history invader ladder landmark landscape mankind marvel ming mongolia mountain mud neolithic ning ningxia old ordos oriental path peking postcard prefecture protection qin rampart ridge river ruin ruins scape scene scenic shui shuidonggou sky steps stone tourist travel view wall war water winter wonder world xia yellow yin yinchuan