Qinling–Huaihe Line

The line has served as the border between northern and southern Chinese dynasties: between the Northern and Southern dynasties of c. 3th–6th century and between the Southern Song of c. 13th century and its northern neighbor Jin dynasty.

Historically, due to being the Cradle of Chinese Civilization, the North had been more developed than the South. That has changed over time and three of the four most developed Tier 1 cities in China are in the South. It was in the Ming dynasty that the economy of the South started to outpace the economy of the North.[1][5] The gross regional product (GRP) of provinces and counties below the line was equal to those above the line in 1960, but by 2019, the south's GRP had become 83% larger than the north's.[4]

The Qinling–Huaihe Line was defined by Chinese geographer Zhang Xiangwen in 1908, defining north China as anything above a line running along the Qinling Mountains in the west and the Huai River the east.[6]

In the 1950s, Premier Zhou Enlai used the line to create a subsidized district heating system only in the colder north, a system still in effect today.[7][8] This has led to the north suffering from heavy air pollution due to coal heating plants, while the south suffers from lack of heating during the winter months.[9]

The line is attributed with serving as a division line in the hydrology and climatology of China. It roughly coincides with:[10]

• the 800 mm (31 in) annual precipitation line (isohyet) of China; by extension, the division between China's humid and semi-humid areas and rice or wheat production areas;
• the 0 °C (32 °F) average January temperature (isotherm) line of China; by extension, China's subtropic zone;
• the division between the drainage basins of the Yangtze and Yellow Rivers.

• Heihe–Tengchong Line, divides China in eastern and western halves
• Mason–Dixon line, North American counterpart