1882, G. W. Keeton, “Regulations for Maritime and Overland Trade between Chinese and Korean Subjects, 1882”, in The Development of Extraterritoriality in China[1], volume II, Longmans, Green & Co., published 1928, →OCLC, page 341:
Article V.—In consideration of the numerous difficulties arising from the authority exercised by local officials over the legal traffic at such places on the boundary as I-chou, Hui-ning, and Ch’ing-yuan, it has now been decided that the people on the frontier shall be free to go to and fro and trade as they please at Ts’e-men and I-chou on the two sides of the Ya-lu River, and at Hun-ch’un and Hui-ning on the two sides of the T’u-men River.
Furthermore, border trade between the two countries was conducted at Chunggang (Chung-chiang), a small island in the estuary of the Yalu, Hoeryŏng (Hui-ning), and Kyŏng’wŏn (Ch’ing-yüan). The last two places are in the lower Tumen valley.
1970, Robert H. G. Lee, “The Geographic and Cultural Foundation of the Chʼing Manchurian Frontier Policy”, in The Manchurian frontier in Chʼing history[3], Cambridge, Mass.: Harvard University Press, →ISBN, →LCCN, →OCLC, pages 10–11:
Every year on the tenth lunar month, a trade expedition was sent to Hoi Ryong (Hui-ning in Chinese), a Korean border town, located on the bank of the Tumen River, southeast of Ninguta, where salt, rice, iron, cloth, paper, cattle, and horses were obtained.
