The Huai River (Chinese: 淮河; pinyin: Huái Hé) is a major river in China. It is located about mid-way between the Yellow River and Yangtze, the two largest rivers in China, and like them runs from west to east. The Huai is notoriously vulnerable to flooding.The Huai River-Qin Mountains line is generally regarded as the geographical dividing line between Northern and southern China. This line approximates the 0 degree January isotherm and the 800 mm isohyet in China. It also reflects the boundary established in 1142 by the Treaty of Shaoxing between the Jin dynasty in North China and the Southern Song in South China.The Huai River is 1,110 kilometres (690 mi) long with a drainage area of 174,000 square kilometres (67,000 sq mi).