[1] The name Unsan is proposed to have been derived from either the Chinese character 银 or 隐, both read as "un" in Korean, referring to the possibility of silver being mined in a mine located in Sinchang, or 'hidden', as the area is surrounded by mountains, such as Hwasan.

[2] Hungdok-gun, the predecessor to the current administrative division, was formed in the early Goguryeo period from Sunchon-gun.

In 1414, after the establishment of the Joseon, it was briefly absorbed into Chasan-gun, then reestablished in 1415.

[2] By the 1990s, Kubong-rodongjagu had been developed into a large mining town, with over 4600 residences and various services, such as hospitals, culture halls and schools.

This line had a stated length of 10-ri with 4 stops, connecting the workers' district to the entrance 2nd pit of Ryongdae Mine.