Physical Region
The vast land expanses of China include plateaus, plains, basins, foothills, and mountains. Defining rugged plateaus, foothills and mountains as mountainous, they occupy nearly two-thirds of the land, higher in the West and lower in the East. The highest step of the typical 'ladder topography' is formed by the Qinghai-Tibet Plateau at the average height of over 4,000 meters, with the Kunlunshan range, Qilianshan range and Hengduan mountain chain as the division between this step and the second one. The highest peak in the world, Everest, at 8844.43 meters high is known as 'the Roof of the World'. China has numerous rivers and lakes. According to statistics, more than 50,000 rivers have drainage areas that exceed 100 square kilometers; more than 1,500 exceed 1,000 square kilometers. These rivers can also be classified as exterior and interior rivers. Lakes are also important. The areas with the most lakes are the Middle-Lower Yangtze Plain and Qinghai-Tibet Plateau. Many lakes in the northwest are salty.