Ussuri River in the context of "Primorsky Krai"

Outer Manchuria, sometimes called Russian Manchuria, refers to a region in Northeast Asia that is now part of the Russian Far East but historically formed part of Manchuria (until the mid-19th century). While Manchuria now more normatively refers to Northeast China, it originally included areas consisting of Priamurye between the left bank of Amur River and the Stanovoy Range to the north, and Primorskaya which covered the area in the right bank of both Ussuri River and the lower Amur River to the Pacific Coast. The region was ruled by a series of Chinese dynasties and the Mongol Empire, but control of the area was ceded to the Russian Empire by Qing China during the Amur Annexation in the 1858 Treaty of Aigun and 1860 Treaty of Peking, with the terms "Outer Manchuria" and "Russian Manchuria" arising after the Russian annexation.

Prior to its annexation by Russia, Outer Manchuria was predominantly inhabited by various Tungusic peoples who were categorized by the Han Chinese as "Wild Jurchens". The Evenks, who speak a closely related Tungusic language to Manchu, make up a significant part of the indigenous population today. When the region was a part of the Qing dynasty, a small population of Han Chinese men migrated to Outer Manchuria and married the local Tungusic women. Their mixed descendants would emerge as a distinct ethnic group known as the Taz people.

Khabarovsk (Russian: Хабаровск [xɐˈbarəfsk] ) is the largest city and the administrative centre of Khabarovsk Krai, Russia, located 30 kilometers (19 mi) from the China–Russia border, at the confluence of the Amur and Ussuri Rivers, about 800 kilometers (500 mi) north of Vladivostok. As of the 2021 Russian census, it had a population of 617,441. It was known as Khabarovka until 1893.

The city was the administrative center of the Far Eastern Federal District of Russia from 2002 until December 2018, when the status was given to Vladivostok. As is typical of the interior of the Russian Far East, Khabarovsk has an extreme climate with strong seasonal swings resulting in strong, cold winters and relatively hot and humid summers.

The Wild Jurchens (Chinese: 野人女真) or Haidong Jurchens (Chinese: 海東女真) were a group of the Tungusic peoples in Northeast Asia identified by the Ming dynasty as the northernmost of the three groups of Jurchen people (the other two being the Jianzhou Jurchens and Haixi Jurchens). In the 14th century, they inhabited the northernmost part of Greater Manchuria from the western side of the Greater Khingan Range to the Ussuri River and the lower Amur River bordered by the Tatar Strait and the Sea of Japan.

The descendants of Wild Jurchens do not identify themselves as Manchus. Instead, they formed different nations such as Nanai, Evenks, Negidals, Oroqen and Nivkh.

The Sino-Soviet border conflict, also known as the Sino-Soviet crisis, was a seven-month undeclared military conflict between the Soviet Union and China in 1969, following the Sino-Soviet split. The most serious border clash, which brought the world's two largest socialist states to the brink of war, occurred near Damansky (Zhenbao) Island on the Ussuri (Wusuli) River in Manchuria. Clashes also took place in Xinjiang.

In 1964, the Chinese revisited the matter of the Sino-Soviet border demarcated in the 19th century, originally imposed upon the Qing dynasty by the Russian Empire by way of unequal treaties. Negotiations broke down amid heightening tensions and both sides began dramatically increasing military presence along the border. Sino-Soviet relations worsened further following the Soviet invasion of Czechoslovakia in 1968. Border confrontations escalated in March 1969 when a group of People's Liberation Army troops engaged Soviet border guards on Zhenbao Island in Manchuria, resulting in considerable casualties on both sides. Further clashes occurred in August at Tielieketi in Xinjiang and raised the prospect of an all-out nuclear exchange. The crisis de-escalated after Soviet Premier Alexei Kosygin met with Chinese Premier Zhou Enlai in September, and a ceasefire was ordered with a return to the status quo ante bellum.

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.

The Udege (Russian: Удэгейцы; Udihe: удиэ or удиһе, or Udihe, Udekhe, and Udeghe correspondingly) are a native people of the Primorsky Krai and Khabarovsk Krai regions in Russia. They live along the tributaries of the Ussuri, Amur, Khungari, Samarga, and Anyuy Rivers. The Udege speak the Udege language, which belongs to the Tungusic language family. Their religious beliefs include animism, animal worship, and shamanism. The Udege are mainly engaged in hunting, fishing, and ginseng harvesting. According to the 2002 census, there were 1,657 Udege in Russia, a slight increase from 1,500 in 1970. This was down to 1,496 Udege in Russia in the 2010 census. They are one of the closest ethnic groups to the Manchu and Nanai, and are possibly of Xi Yeren Jurchen origin.

The Udege of the Samarga River basin had lived in dispersed encampments all along the tributaries of the river until about the 1930s. Under Soviet collectivization the Udege in the area were concentrated in four villages with Agzu being the largest (2010 census about 150).