Often used as the geographical dividing line between northern and southern China is the
Qin Mountains Line. This line approximates the 0 °C January
isotherm and the 800 millimetres (31 in)
isohyet in China.
Culturally, however, the division is more ambiguous. In the eastern provinces like
Yangtze River may instead be perceived as the north–south boundary instead of the Huai River, but this is a recent development.
There is an ambiguous area, the region around
Nanyang, Henan, that lies in the gap where the Qin has ended and the Huai River has not yet begun; in addition, central Anhui and Jiangsu lie south of the Huai River but north of the Yangtze, making their classification somewhat ambiguous as well. As such, the boundary between northern and southern China does not follow provincial boundaries; it cuts through
Shaanxi, Henan, Anhui, and Jiangsu, and creates areas such as
Huaibei (Anhui) and
Xuzhou (Jiangsu) that lie on an opposite half of China from the rest of their respective provinces. This may have been deliberate; the
Yuan dynasty and
Ming dynasty established many of these boundaries intentionally to discourage regionalist
The Northeast (
Inner Mongolia, areas that are often thought of as being outside "
China proper", are also conceived to belong to northern China according to the framework above. Historically,
Qinghai were not usually conceived of as being part of either the north or south. However, Xinjiang is now regarded as being part of the north due to the spread of north Chinese culture and the use of Mandarin.