Location and origin
Gando is the name Koreans use to refer to the parts of Manchuria long inhabited by Koreans. There is not a uniform definition of how much of Manchuria that Gando consists of. Most likely, it refers to the Chinese provinces of Jilin and Heilongjiang. The name which literally means "Between Island" thus most likely refers to the fact that this area is surrounded by the rivers Tumen, Songhua, and Heilongjiang.
Korean history in Manchuria
Setting the boundary
In 1712, Joseon of Korea and Qing of China agree to set the boundaries of the two countries at Yalu and Tumen Rivers. The Yalu (鴨綠) / Amnok (압록) River boundary is of little dispute, but the interpretation of the Tumen causes problems. On the original document, Tumen is written as 土門 (토문), which would refer to a small river that joins the Songhua (松花) / Songhwa (송화) River. However, Qing officials would later claim that Tumen (豆滿) / Duman (두만) River is the boundary on record. This confusion is brought up as the two names sound identical, and neither name is actually of Chinese origin (only using Chinese homophones). The two rivers can be seen in the following picture.
According to various maps produced in late 18th and 19th centuries, different maps show different ideas of Gando.
In the following maps, slightly different boundaries are shown to represent Gando.
(Map 2: late 18th century English origin; Map 3: early 19th century German origin; Map 4: mid 19th century Russian origin)
Between 1931 to 1945, Manchuria was under the control of Manchukuo, a Japanese client state. Gando (間島省) was a province of Manchukuo. The area reverted to Chinese control after the end of World War 2. This area is now the Yanbian Korean Autonomous Prefecture in Jilin province. The province containing Gando has been highlighted on this map of Manchukuo's administrative divisions.
Settling the area
For years, Qing officials did not allow people to move to Manchuria, as it always believed that should a Han majority government rise again in China, the Manchu royalty can flee to this area and retain a strong base to recover control in China. Joseon officials also did not allow its subjects to move to Manchuria. These governmental regulations with the general marshy nature of the area left Gando undeveloped and sparsely inhabited for long time. However, by late 19th century, significant amount of Koreans were living in Gando, and even more arrived as Korea became a colony of Japan in 1910. After World War II and the liberation of Korea, many Korean expatriates moved back, but a significant majority still remained in Gando; descendants of these people form the Korean ethnic minority in China today.
In 1905, Joseon (at this time as the Korean Empire) becomes a protectorate of Japan, effectively losing diplomatic rights. On 18 April 1906, a team of Japanese military invaded Gando and declared ownership over the region. In 1909, Japan affirmed territorial rights of Qing over Gando after the Chinese foreign ministry issued a thirteen-point "refutation" statement regarding its rightful ownership. Despite these changes, the inhabitants of Gando were mostly Koreans and the area remained under significant Korean influence. In the following 1924 map from "Catholicisme en Corée", a guide to French Catholic missionaries to Korea, Gando is clearly put under the Apostolic vicariate (special type of diocese for non-Catholic regions) of Wonsan erected in 1920.
(At this time, Korea is divided under three Apostolic vicariates; Seoul (originally Corea) erected in 1831 by Pope Gregory XVI, Daegu erected in 1911 by Pope Pius X, and Wonsan erected in 1920 by Pope Benedict XV.)
Loss of control
After liberation of Korea in 1945, many Koreans believed that Gando should be returned to Korean rule, but the military control by United States of America in the south and Union of Soviet Socialist Republics in the north hindered any unified Korean claim to the territory. The following chaos of the Korean War and the geopolitical situation of the Cold War effectively diminished any public outcry for the return of Gando. In 1962, North Korea signed a boundary treaty with People's Republic of China setting the Korean boundary at Yalu and Tumen, effectively foregoing territorial rights to Gando. South Korea also recognizes this as the boundary between Korea and China.
It has been claimed that since Japan ceded all territories outside Japan after the end of World War II, the sale of Gando to China can be claimed null and void under international law. However, none of the governments involved (North Korea, South Korea, People's Republic of China, or Japan) make such a claim. In addition, there is very little enthusiasm for irredentism among the Korean minority in China. Although there are occasional arguments over historical interpretation, this issue arouses very little emotion or official interest on the part of any of the parties, and relations between China and both Koreas remain warm.
A small number of South Korean activists believe that under a unified Korea, the treaties signed by North Korea can be deemed null, allowing the unified Korea to actively seek regress for Gando. However, the current political situation make this a faint possibility at best.
Some scholars claims that China's efforts to incorporate the history of Goguryeo and Barhae into Chinese history is an effectively pre-emptive move to squash any territorial disputes that might rise regarding Gando before a unified Korea can claim such or the Korean ethnic minority in the Manchuria region claim to become part of Korea.