Within the province, it borders Hyangsan to the east, Kujang and Nyŏngbyŏn to the south, and Tongch'ang and T'aech'ŏn to the west.

The region was known as Unjung County or Gowonhwajin during the Early Goryeo period but later got the name Wihwajin in 968.

In 995, the region changed its name to Unju, and a defense institution was installed to ward off the invasions of the khitans in the north.

In 1231, the residents of the region evacuated to Haedo island to escape the invading Mongols and temporarily stayed in a town west of Gasan (a town in Pyongan province), but later became incorporated into Yeonsanbu (a subdivision part of modern-day Yongbyon) but it separated to its own subdivision in 1271.

[2] In 1895, after a drastic change in subdivisions as a consequence of the Gabo reforms, Unsan County became part of the Department of Uiju (modern-day Sinuiju).

In July 1895, the Joseon dynasty signed a treaty with American businessman James R. Morse regarding the mining of gold in the region and established a joint corporation called the Oriental Consolidated Mining Company (OCMC,동양합동광업회사) in April 1896.

Of Unsan's cultivated land, most (70%) is dry-field, with numerous cattle farms; local crops include maize, soybeans, sweet potatoes, and vegetables as well as rice.