In 1616, the 44th year of the Wanli reign, and 1618, the 46th year of the Wanli reign, Xu Xiake, a famous traveller and geographer of the Ming dynasty, ascended Mount Huangshan. He wrote two famous travel books, in which he revealed three geographical secrets of Mount Huangshan: 1) Guangmingding, Pingtiangang, Qianhai and Houhai are level areas 1,600-1,800 m above sea level surrounded by steep cliffs; 2) the Taohua Peak and Yunmen Peak of Mount Huangshan are the watershed between the Yangtze River and the Qiantang River; and 3) the Lianhua Peak is higher than the Tiandu Peak, and is the highest peak of Mount Huangshan.