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
Gobi Desert Water is scarce, with no streams, no lakes, no wells, and precipitation falls seldom. The prevailing winds blow from the west and northwest, and the pall of dust overhangs the country as in the Takla Makan and the desert of Lop. Characteristic of the flora are wild garlic, "Kalidium gracile", wormwood, saxaul, "Nitraria schoberi", "Caragana", Ephedra, saltwort and the grass "Lasiagrostis splendens". The taana wild onion "Allium polyrrhizum" is the main browse eaten by many herd animals, and Mongolians claim that this is essential to produce the correct, slightly hazelnut-like flavour of camel airag (fermented milk). This great desert country