Seogando Island and Donggando Island (Northern Island) are separated.

 Is Seogando Island different from Gando Island, marked on the map of Korea, China, Japan, and Europe in the western part of Baekdusan Mountain and the northern part of the Yalu River? What else happens to the sovereignty?" The nomination of "Gando" causes a lot of confusion. Originally, "Gando" refers to the delta in the middle of the Tuman River flowing between Jongseong-gun and Onseong-gun, North Hamgyeong Province, and the population clearing the land across the Tuman River has soared since the 19th century, and all fertile land east of Baekdusan Mountain has been called "Gando." It was also called "Gando" in the sense of land settled and reclaimed by our people. There has also been an example of calling the entire Manchuria area "Gando." The area we usually call "Gando" is currently a Korean-Chinese autonomous region along the coast of Jilin Province, China, and corresponds to the "Donggando" area. Seogando Island, west of Baekdusan Mountain, is a different area. However, in many records and maps of Korea, China, Japan, and the West, the "Seogando" area north of the Yalu River is also marked as Joseon territory. A map of the Joseon Kingdom drawn by French geographic researcher D'Anville in 1737, a map of Du Halde and Bogondi in France (1740), a map of Wilkinson (1794), a map of England, and a Map of Hwang Yeo-in produced in the Qing Dynasty in 1716, a map of Japan. The Cheongdae librarian "Gilim Notice" wrote that "Chosun's change encountered Shenyang and Gilim." What was the identity of this border drawn north of the Yalu River? Experts believe that since the Ming Dynasty, the Chinese side installed fences in Liaodong, about 120 ri north of the Yalu River, and the Chinese-Chinese border planted willow trees and sold trenches here in the 1660s. This border is the "Regisun" drawn on the actual map of Regis, a French missionary who wrote a change map from 1708 to 1716 under the order of Cheonggangheeje, and this line is drawn north of the Yalu River and the Tuman River. There were 37,000 Koreans who migrated to areas such as Gyeonghwa and Hwanin in Seogando Island, and in 1903, the Joseon government dispatched officials from both sides to unite Korean villages in Seogando Island to implement the Hyangyak system. On the other hand, Bukgando Island is a word commonly used in the same meaning as Donggando Island. However, when the northern Manchuria area, such as Harbin and Gilim, is usually referred to as Bukgando Island, it refers to the eastern part of the Songhwagang River, north of the Korean-Chinese Autonomous Region along the coast. This geographical concept is largely consistent with a map published in the Catholic Church of Korea published by the French Church of Foreign Affairs in Paris in 1924 depicting the area of the Joseon Diocese to a part of the Heukryonggang River.