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
Gurbantünggüt Desert but now has mostly dried out, and the Ailik Lake (), which receives water from the Baiyang River (which in its turn is replenished by the Irtysh–Karamay Canal). China National Highway 216 crosses the desert in the north-south direction, from Altay City to Ürümqi. China National Highway 217 and the Kuytun–Beitun Railway skirt it from the west and northwest. The Ürümqi–Dzungaria Railway reaches into the desert's southeastern corner, known locally as "Jiangjun Gobi" (将军戈壁, "General's Desert"). The climate of the area is temperate, but very continental. The desert's ecological environment is very fragile, and the impact of human activities on