The region that forms modern day Kosong County of North Korea and Hyeonnaemyeon(of Goseong County, Gangwon) was called Dalhol(達忽,달홀) in the days of the kingdom of Goguryeo,which meant "high mountainous village" in the local language back then(The region that is modern day Goseong County, Gangwon of South Korea was called Suseong(守城)).The name of the region was changed to dalhol province in 568.

This name was changed to Kosong(高城) County in 748 under the kingdom of Unified Silla, which meant the same thing but instead of the local language, but in hanja.

Kosŏng is largely mountainous, but there is flat land along the coast of the Sea of Japan to the county's east.

[7] Ch'ogu-ri(草邱里,초구리) is a village named as such for its grassy mounds, which originally formed the subdivision of Anchangmyeon.

Sunhang-ri(순학리) is a newly formed town in 1952 from Chohyonri of Sudongmyeon and Jeonseongri and Songtanri of Seomyeon.The village was named after Choi soon ak( Hero of the Republic winner), a soldier of the KPA, who fought in the battle of hill 351 during the Korean war.

[15] The local economy is dominated by agriculture, although fishing also plays a role, together with the harvesting of brown seaweed and clams.

Nearly half the length of the Kŭmgangsan Ch'ŏngnyŏn line of the Korean State Railway is in Kosŏng county.

[16] The section between Kŭmgangsan Ch'ŏngnyŏn and Jejin stations was out of service from the partition of Korea until 2007, when it was reopened for passenger trains from the South to the Mount Kŭmgang Tourist Region; it was closed again after the shooting of a South Korean tourist by a KPA soldier.