This is the 14460th most frequent Korean word.
문산
"문산" is the name of a town in South Korea, specifically in Paju, Gyeonggi Province.
Here, '문산' is used as a proper noun referring to a location (Munsan).
문산에 가는 기차를 잡았습니다.
I caught the train going to Munsan.
In this sentence, '문산 시장' refers to a market located in Munsan, again, used as a geographical location.
우리는 문산 시장에서 몇 가지 물품을 구매했습니다.
We purchased some items at the Munsan market.
Here, '문산' is used to refer to the name itself and its familiarity to people.