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 antelopes and wild camels, which frequent its few small, widely scattered oases. The vegetation, which is confined to these same relatively favoured spots, is of the scantiest and is mainly confined to bushes of saxaul "(Haloxylon)", "anabasis", reeds (kamish), tamarisks, poplars, and Ephedra. The Gobi had a long history of human habitation, mostly by nomadic peoples. By the early 20th century, the region was under the nominal control of Manchu-China, and inhabited mostly by Mongols, Uyghurs, and Kazakhs. The Gobi Desert as a whole was known only very imperfectly to outsiders, and information was confined to observations by individual travellers