The DMZ was created by the Korean Armistice Agreements, which was signed on July 27, 1953. Specifically, the Armistice created a 155-mile long military demarcation line (MDL) with a 2-kilometer deep demilitarized zone on each side of it (for a total width of 4 kilometers), where all military operations and hostile acts ceased. This area is the DMZ.

The MDL starts in Kyodongdo, near the intersection of the Imjin and Han Rivers in the neutral Han River Estuary, and runs to Kosong-gun, Kangwon Province, via Panmunjom south of Kaesong, Chorwon, Kimhwa and Myunghori. Overall it runs across the waist of the Korean peninsula for about 248 kilometers. When we think of the MDL, we usually think of a line divided by military fences, barbed wire entanglements, however the MDL is simply marked by yellow signs called MDL Markers.

The MDL Markers are written in Korean and English on the southern side and in Korean and Chinese on the northern side. This was done with respect to the languages of major participants in the Korean War.

The MDL Marker numbering begins with 0001 at its western end where it intersects the Imjin River and ends at the East Sea. There were a total of 1,292 MDL Markers placed at approximately 200 meter intervals.

Of these 1,292 markers, the United Nations Command (UNC) forces are responsible for maintaining 696 markers and the Communist armies are responsible for the maintenance of 596 markers.

A barbed wire fence, often called the iron fence line, is set up approximately 2 kilometers away from the MDL in the vicinity of the respective boundaries of the DMZ. These lines are called the Southern Boundary Line and the Northern Boundary Line.