Jiandao or Chientao, known in Korean as Gando or Kando, is a historical border region along the north bank of the Tumen River in Jilin Province, Northeast China that has a high population of ethnic Koreans. The word "Jiandao" itself, literally "Middle Island", was initially referred to a shoal in Tumen River between today's Chuankou Village, Kaishantun in Longjing, Jilin, China and Chongsŏng, Onsong County in North Korea. The island was an important landmark for immigrants from the Korean Peninsula looking for settlements across the river. As the number of immigrants increased, the area that the word "Jiandao" gradually changed to reflect the areas of Korean settlement. In the early 20th century, an expanding Japanese Empire argued that ethnic Koreans living in this area should be placed under its jurisdiction. As one of its first set of attempts to annex northeast China and conquer other parts of mainland China, Imperial Japanese forces in Korea invaded Jiandao in 1907, but Japan withdrew its forces to Korea in 1909 and recognized the border that was present along Tumen River before the invasion, under diplomatic pressure from China. The Yanbian Korean Autonomous Prefecture of present-day Jilin Province covers roughly the same region as historical Jiandao. The prefecture is approximately 42,000 square kilometers in size and home to about 810,000 ethnic Koreans. In China, Yanbian is the name used, and Jiandao is not used, due to its association with Japanese colonial occupation. Both North Korea and South Korea recognize the region as a part of the People's Republic of China, but there are some liberal and left-wing nationalist elements in South Korea that endorse the idea that the region should be a part of modern-day Korea. These groups claim what happened in Jiandao between 1907–1909 (Japan's invasion and subsequent withdrawal) was an illegal transfer of Korean territory between Japan and China. History Many different states and tribes succeeded each other in ruling the area during ancient times. These included Buyeo, Goguryeo and Goguryeo's successor state Balhae. Goguryeo was a country that controlled northern Korea and southern Manchuria, being widely regarded as one of the Three Kingdoms of Korea. Balhae was a state that existed in the area during the Tang dynasty in China and the Unified Silla Period in Korea. China emphasizes Balhae's temporary tributary relationship to the Tang, while Korea emphasizes that Balhae was a successor state and a cultural extension of Goguryeo.