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
Deforestation and climate change or forests. Although China has set official goals for reforestation, these goals were set for an 80-year time horizon and were not significantly met by 2008. China is trying to correct these problems with projects such as the Green Wall of China, which aims to replant forests and halt the expansion of the Gobi Desert. A law promulgated in 1981 requires that every school student over the age of 11 plant at least one tree per year. But average success rates, especially in state-sponsored plantings, remains relatively low. And even the properly planted trees have had great difficulty surviving the