Heihe–Tengchong Line in the context of "Aihui District"

The Qinling–Huaihe Line (Chinese: 秦岭淮河线; pinyin: Qínlǐng Huáihé Xiàn) is a reference line used by geographers to distinguish between northern and southern China, corresponding roughly to the 33rd parallel. Qinling refers to the Qin Mountains, and Huaihe refers to the Huai River. Running from Qin Mountain in the west to Huai River in the east, it divides eastern China into northern and southern regions that differ from each other in climate, culture, lifestyle, and cuisine.

Regions north of the Line tend to be temperate or continental, with snow being a regular feature in winter. Regions south of the Line tend to be subtropical or tropical. In general, the southern region is hotter, wetter, and much more hilly than the northern region.

Heihe (Chinese: 黑河; pinyin: Hēihé; lit. 'Black River'; Russian: Хэйхэ) is a prefecture-level city of northern Heilongjiang province, China, located on the Russian border, on the south bank of the Amur (Heilong) River, across the river from Blagoveshchensk. At the 2020 census, 1,286,401 people lived in the prefecture-level city of whom 223,832 lived in the built-up area (or metro) made of Aihui District.At the end of 2024, the resident population of the city will be 1.23 million, including 823,000 in urban areas and 407,000 in rural areas.

Heihe marks the northeast terminus of the diagonal Heihe–Tengchong Line, which is sometimes used to divide China into east and west.