Songhua River in the context of "China–North Korea border"

The Northeast China Plain (simplified Chinese: 东北平原; traditional Chinese: 東北平原; pinyin: Dōngběi Píngyuán), also known as Songliao Plain, Manchurian Plain, or Northeast Plain, is located in Northeast China. It lies between the Greater and Lesser Khingan and Changbai mountains, ending at the coast at Liaodong Bay in the Bohai Sea. Covering 350,000 km, it is China's largest plain, with an elevation of lower than 200 meters, and less than 100 meters to the southwest. The Songhua, Nen, and Liao Rivers run through the plain.

The Northeast Plain includes Songnen Plain in the north, Liaohe Plain in the south, and Sanjiang Plain in the northeast. The Songnen Plain was formed by the Songhua and alluvial soils from the Nen. The Liaohe Plain, located in the hilly areas near Changchun, was created by the separation of watersheds of the Songhua and Liao, which are collectively known as the Liaohe Plain. The Sanjiang Plain, at the confluence of the Songhua, Amur, and Ussuri Rivers, was originally a swamp known as the "Great Northern Wilderness", becoming a food-producing area after reclamation. The original wetland area of the Sanjiang Plain has been greatly reduced.

Paektu Mountain or Baekdu Mountain (Korean: 백두산) is an active stratovolcano on the Chinese–North Korean border. In China, it is known as Changbai Mountain (Chinese: 长白山). At 2,744 m (9,003 ft), it is the tallest mountain in North Korea and Northeast China and the tallest mountain of the Baekdu-daegan and Changbai mountain ranges. The highest peak, called Janggun Peak, belongs to North Korea. The mountain notably has a caldera that contains a large crater lake called Heaven Lake, and is also the source of the Songhua, Tumen, and Yalu rivers. Korean and Manchu people assign a mythical quality to the mountain and its lake, and consider the mountain to be their ancestral homeland.

The mountain's caldera was formed by an eruption in 946 that released about 100–120 km (24–29 cu mi) of tephra. The eruption was among the largest and most powerful eruptions on Earth in the last 5,000 years. The volcano last erupted in 1903, and is expected to erupt around every hundred years. In the 2010s, concerns over an upcoming eruption prompted several countries to commission research into when the volcano might next erupt.The mountain is considered culturally important to multiple groups in the area, including Korean, Chinese, and Manchu people. The mountain is a major national symbol for both North and South Korea, and is mentioned in both national anthems and depicted on the national emblem of North Korea. The Manchu people also consider the mountain their ancestral homeland, and the Chinese Qing dynasty saw it as a symbol of imperial power and the mountain had been subject to territorial disputes over the past few centuries. In the late 20th century, the states of China and North Korea diplomatically agreed to joint custody.

The Harbin cranium is a nearly complete skull of an archaic human found in sediments of the Songhua River near Harbin on the Northeast China Plain, dating to at minimum 146,000 years ago during the Middle Pleistocene. It was described in 2021, and that year it was assigned as the holotype of the new human species Homo longi ("dragon man") named after Long Jiang, where the fossil skull was discovered . The Harbin cranium was initially hypothesized to belong to the same species as the Denisovans, and subsequent proteomics and mitochondrial DNA analyses confirmed its Denisovan affinities.

The Harbin cranium is broadly anatomically similar to other Middle Pleistocene Chinese specimens. Like other archaic humans, the skull is low and long, with massively developed brow ridges, wide eye sockets, and a large mouth. The skull is the longest ever found from any human species. Like modern humans and the much earlier Homo antecessor, the face is rather flat, but with a larger nose. The brain volume was 1,420 cc, within the range of modern humans and Neanderthals.

Harbin is the capital of Heilongjiang, China, and the largest city of the province—as well as the second largest urban population (after Shenyang, Liaoning province) and the largest metropolitan population (urban and rural regions together) in Northeast China. Harbin has direct jurisdiction over nine metropolitan districts, two county-level cities, and seven counties. It is the eighth most populous Chinese city according to the 2020 census. The built-up area of Harbin (which consists of all districts except Shuangcheng and Acheng) has 5,841,929 inhabitants, while the total metropolitan population is up to 10,009,854, making it one of the 100 largest urban areas in the world. Harbin serves as a key political, economic, scientific, cultural, and communications hub in Northeast China, as well as an important industrial base of the nation.

Several different etymologies have been offered for the city's name. The city government says the name means "swan" in the Jurchen language, and other sources say that it comes from a Manchu word meaning "a place for drying fishing nets". The settlement grew from a small rural fishing village on the Songhua River to become one of the largest cities in Northeast China. Founded in 1898 with the coming of the Russian-built Chinese Eastern Railway, the city first prospered as a settlement inhabited by an overwhelming majority of immigrants from the Russian Empire. In the 1920s the city was considered China's fashion capital, since new designs from Paris and Moscow reached here first before arriving in Shanghai. From 1932 until 1945, Harbin was the largest city in the Japanese puppet state of Manchukuo. Well known for its historical Russian legacy and architecture, the city is famed for its European influence and serves as an important gateway in Sino-Russian trade today.

The Nen River or Nenjiang (Chinese: 嫩江; pinyin: Nèn Jiāng; Wade–Giles: Nen-chiang), or Nonni (Manchu: ᠨᠣᠨ
ᡠᠯᠠ, Möllendorff: non ula, Abkai: non ula) is a river in Northeast China. The Nen River flows through the northern part of Heilongjiang Province and the northeastern section of Inner Mongolia, some parts of the river forming the border between the two regions. At 1,370 km (850 mi) in length, the Nen River is the longest tributary of the Songhua River.

The Nen River flows in the general southern direction in a wide valley between the Greater Khingan and the Lesser Khingan mountain ranges in the west and east, respectively, and meets the Second Songhua River near Da'an to form the Songhua River.

The Songnen Plain (Chinese: 松嫩平原; pinyin: Sōngnèn Píngyuán) in Northeast China is named after the Songhua and Nenjiang Rivers and is connected to the Sanjiang Plain through the Songhua River Valley; a small plain lies north of Xingkai Lake in the east.

The Sanjiang Plain (Chinese: 三江平原; lit. 'three rivers plain') is a fluvial plain around the confluences among the Amur River, Songhua River and Ussuri River in Northeast Asia, encompassing about 109,000 km (42,000 sq mi) with extensive wetlands.. The plain is located within a basin east of the Lesser Khingan Range, south of the Bureya and Badzhal Ranges, west of the Sikhote-Alin, and north of the Wanda Mountains. The southwestern portion of the plain upstream of and between the courses of the Amur and Ussuri belongs to China, encompassing 23 counties of the Heilongjiang province; while the rest of the region belongs to the Jewish Autonomous Oblast and Khabarovsk Krai of Russia's Far Eastern Federal District.

Elopichthys is a monospecific genus of freshwater ray-finned fish belonging to the family Xenocyprididae, the East Asian minnows or sharpbellies. The only species in the genus is Elopichthys bambusa, the yellowcheek or kanyu (Chinese: 鱤魚; pinyin: gǎnyú), a large fish that is found in freshwater habitats in eastern Asia. It ranges from the Amur River in Russia, through China to the Red and Lam Rivers in Vietnam. It prefers relatively warm waters, entirely avoiding colder highlands. It is considered an important food fish where it occurs, reaching up to 2 m (6 ft 7 in) in total length and 52.2 kg (115 lb) in weight.

This fish spawns in the summer, mainly in streams in places like the mid-Amur, Songhua and Ussuri basins. In the Amur, young are found in the lower sections. They mature after 6 years, and after this time they tend to live in floodplains and winter in the main rivers. This is a fast and agile predator. They mainly consume smaller fish.

The Mohe, Malgal, Mogher, or Mojie were historical groups of people that once occupied parts of what is now Northeast Asia during late antiquity. The two most well known Mohe groups were known as the Heishui Mohe, located along the Amur River, and the Sumo Mohe, named after the Songhua River. They have been traditionally defined by the approximate use of what would have been Tungusic languages. The Heishui Mohe are commonly thought as being direct ancestors to the 12th century Jurchens. The Tang documented the Mohe as inhabiting the land of Sushen, to the northeast of the Tang, east of the Turks, and north of Goguryeo.

The Mohe constituted a major part of the population in the kingdom of Balhae in northeast Asia, which lasted from the late 7th century to early 10th century. After the fall of Balhae, few historical traces of the Mohe can be found, though they are considered to be the primary ethnic group from whom the Jurchen people descended. The Heishui Mohe in particular are considered to be the direct ancestors of the Jurchens, from whom the 17th century Manchu people and Qing dynasty founders originated. The Mohe practiced a sedentary agrarian lifestyle and were predominantly farmers who grew soybean, wheat, millet, and rice, supplemented by pig raising and hunting for meat. The Mohe were also known to have worn pig and dog skin coats.