The Nan Mountains
The Nan Mountains (Nan Ling) are composed of many ranges of mountains running from northeast to southwest. These ranges form the watershed between the Yangtze to the north and the Pearl (Zhu) River to the south. The main peaks along the watershed are above 5,000 feet, and some are more than 6,500 feet. But a large part of the land to the south of the Nan Mountains is also hilly; flatland does not exceed 10 percent of the total area. The Pearl River Delta is the only extensive plain in this region and is also the richest part of South China. The coastline is rugged and irregular, and there are many promontories and protected bays, including those of Hong Kong and Macau. The principal river is the Xi River, which rises in the highlands of eastern Yunnan and southern Guizhou.