History of the Great Wall of China the three, China's chief concern since the earliest times had been Mongolia – the home of many of the country's fiercest enemies including the Xiongnu, the Xianbei, the Khitans, and the Mongols. The Gobi Desert, which accounts for two-thirds of Mongolia's area, divided the main northern and southern grazing lands and pushed the pastoral nomads to the fringes of the steppe. On the southern side (Inner Mongolia), this pressure brought the nomads into contact with China. For the most part, barring intermittent passes and valleys (the major one being the corridor through Zhangjiakou and the Juyong Pass), the North China
Badain Jaran Desert It is bound to the north by the Gobi and to the East by Mount Lang which separates it from the Ulan Buh Desert (Pinyin: wū lán bù hé shā mò Chinese: 乌兰布和沙漠) Although most of the dunes in the desert are not stationary, the larger ones usually ranging above are static. With these dunes only the shallow surface of the sand is constantly shifting. The middle and lower layers of the highest dunes have been compacted for more than 20,000 years causing the sand particles to harden resulting in solid layers of sand and sandstone. High moisture levels inside