After the Manchu tribes they replaced the Ming dynasty with the Qing. However, the Qing emperors did not fully integrate their homeland into China. This legal and, to a degree, ethnic division persisted until the Qing dynasty began to fall apart in the 1800s.
As the court in Beijing weakened, many outlying regions, such as Kashgar, became independent or fell under the control of the Imperialist powers. In the 1800s, the Russian Empire was most interested in the northern lands of the Qing Empire. In 1958, Russia gained control of a huge track of land called Outer Manchuria thanks to the Supplementary Treaty of Beijing that ended the Second Opium War. Russia was evidently not satisfied by this, and made numerous attempts to control the rest of Manchuria as the Qing Dynasty continued to decline. Inner Manchuria came under a strong Russian influence in the 1890s with the building of the Chinese East Railway through Harbin to Vladivostok.
As a direct result of the Russo-Japanese war, which lasted from 1904 to 1905, Russian influence in Manchukuo was near completely eliminated. In its place, Manchukuo fell under the influence of the Japanese. In1906, Japan laid the South Manchuria railway to Ryojun. During the Chaos of the Russian Civil war, Japan invaded Outer Manchuria. A combination of Russian military success and American pressure forced the Japanese to withdraw again in 1925.
During China's warlord period, the warlord Zhang Zoulin established himself in Inner Manchuria with Japanese backing. Later, the Japanese Kwantung Army found him too independent, and had him assassinated in 1928.
After the Japanese Invasion of Manchukuo in 1931, Japanese militarists moved forward to separate the region from Chinese control and to create a Japanese-aligned puppet state. To create an air of legitimacy, the last emperor of China, Pu Yi, was invited to come with his followers and act as the head of state for Manchuria.
On February 18th, 1932, the Manchu State (alternatively called Manchukuo or the Great Manchu Empire) was proclaimed, recognized by Japan. The city of Changchun, renamed Xinjing, became the capital of Manchukuo. Chinese in Manchuria organized volunteer armies to oppose the Japanese and the new state required a war lasting several years to pacify the country.
The Japanese established Pu Yi, given the Era name Kangde, making Manchukuo formally a monarchy. Zheng Xiaoxu became Prime Minister from 1932 to 1935, when he was succeeded by Zhang Jinghui. No real power was given to the government except in name, leaving Manchukuo in control of the Japanese Military. An Imperial palace was built specially for the emperor. All of the Manchu ministers served as front-men for their Japanese vice-ministers, who made all the decision. In this manner, Manchukuo was separated from China. The final blow to all non-Japanese influence came in 1935, when the Chinese East Railway was purchased from Russia. .
When Japan invaded China, Manchukuo immediately assisted its ally. The Manchu army wouldn't see real front line action for a year after the declaration of war, although there was numerous revolts of Chinese in Manchuria which the military put down. Along with Korea and Japan, Manchukuo supported the founding of the puppet Jinwei government in occupied China.
When the Japanese extended the front to French Indochina and Thailand, Manchukuo was to busy putting down Chinese resistance to join in the fighting. Japan eventually was defeated on these fronts by the British territory of Burma, Thailand and Annamese resistance.
China, supported by the rest of the Allies, managed to push the Sphere forces back to almost the borders they had had before the war's outbreak. The war officially concluded with the Treaty of Tokyo, and the Sphere was forced to pay war reparations to the Allied countries.
After the war, Manchukuo continued its affiliation to the Sphere. The Sphere entered a long period of political and economical competition with the South Asian Union, a conflict which Manchukuo was now a part of.
As the rest of the world recovered from the Great Depression, Asia emerged as an economic powerhouse. Although most of the world sided with the Union, the Sphere did establish several major trading partners.
It was around this time that Manchukuo began to desire real independence. More and more strong politicians rose to power, despite Japan's opposition. After several armed revolts where put down, Japan finally agreed to lower its interference with Manchu politics. Manchukuo became the third true independent nation in the sphere, followed shortly by Korea. In practice, though, Manchukuo was unable to leave the sphere for threat of military and economic exclusion, leaving its foreign policy irrecoverably tied to Japan.