SPACE Magazine
SPACE Magazine
A Spatio- Historical Meaning of the Korean DMZ

A Spatio- Historical
Meaning of the Korean DMZ
Jung Weonjoo (researcher, The Academy of Korean Studies),
Kim Chaehan (professor, Hallym University)

This February and May, SPACE reinvestigated the issues surrounding the DMZ Peace Park and announced a manifesto co-written with experts across diverse fields. This year, another platform from which to continue the discussion on the DMZ was established under the theme ‘The Epoch of Space Politics: What to Do About the DMZ for Peace’ for the 32nd Space Prize for International Students of Architectural Design. In the days leading up to the deadline for the competition in October, SPACE will feature three articles highlighting different aspects of the Peace Park. This series moves beyond a simple repetition of previous studies on the DMZ and promotes valuable discussion from the viewpoints of history, ecology and economics. By observing the characteristics of the DMZ as a doorway to a space-continuum, transcending the historical periods through reflecting on the ‘A spatio-Historical Meaning of the Korean DMZ’, we may begin to understand the implications for the future spaces of the Korean ethnic community, Korea’s reunification and Northeast Asia integration. editorial team

The Korean Demilitarized Zone has long been perceived by many as a border or division line. Some argue that the Korean Peninsula can only be recognised as subject to its own status when the DMZ, which divides Korea into North and South, is abolished. However, it cannot be claimed that the DMZ simply happened overnight in 1953 and that it has only existed for six decades out of the five millennia-long Korean history since Dangun, the legendary founding father of Korea. The 38th parallel, which came to an end during the Korean War, as well as the various partition lines proposed during such wars as the Russo-Japanese War and the Sino-Japanese War, are located around the DMZ.
Above all, the DMZ and its adjacent areas operated as a border for several centuries in the period of the ancient Three Kingdoms (Goguryeo, Baekje, and Silla). Borders between these ancient states were not composed of lines, but of mountains, rivers, roads, gateways, or twilight zones. Most particularly, some fortresses on frontiers performed as key borders.
The DMZ is a typical frontier fortress on the current Korean peninsula. The Korean War Armistice Agreement established the DMZ by making the two combative sides withdraw 2km from the Military Demarcation Line. Thus, the Korean DMZ is composed of areas, not of lines. Though the agreement has never defined the DMZ as a fortress but as a buffer zone, the real Korean DMZ appears to be filled with impenetrable frontier fortresses.
The DMZ and its adjacent areas can be considered to be a gateway to a space-time continuum, in that they were occupied by frontier fortresses in ancient times as well as in the present. The DMZ has been host to so many fierce battles between the Three States (Goguryeo, Baekje and Silla) with the then hegemon (Tang), as well as two Koreas (North and South) with the world powers (United States, China and other major powers). The DMZ and its adjacent areas may be a doorway to a space-continuum in terms of division and unification. Alternatively, the concerns over the current DMZ may have for some a slight sense of déjà vu when they look at the ancient history of the adjacent areas to the Korean DMZ. The purpose of this article is to examine their ancient history, to extract the spatial meanings that transcend the eras, and to imply how the Korean DMZ may evolve for Korean ethnic community, Korea’s reunification, and Northeast Asian integration. It focuses on major rivers and ancient fortresses around the DMZ.


Fig. 1 관미성으로 추정되기도 하는 오두산성이 사진 한가운데 멀리 보인다.

The Armistice Agreement and its annex concur that both sides shall acknowledge the demilitarized and bordering state of the Han River Estuary Area which reaches from the mouth of the Imjin River through the mouth of the Yeseong River. The Yeseong River and the Imjin River were borders to the ancient Three States. Since the historic relics of all three states were found at several sites across the two rivers, the borders among these three states have been contended as they frequently changed depending on the distribution of power; especially as the relics of frontier fortresses act as the strategic sites of value in this area. The fortresses distributed along rivers and traffic routes are presumed to have been built with the design that requires close relationships with each other.
An investigation into the ancient frontier fortresses around the Yeseong River, the Ganghwa Island, the Imjin River and the Hantan River may imply how the DMZ area will evolve in the future. The fact that the river basins have never been excavated owing to the division and its military confrontation does not hinder the prospects of the DMZ’s spatio-history. This is because it may provide a pretext for such cooperative projects as joint excavations by the two Koreas.

The Han River Estuary as Border between Goguryeo and Baekje
The Yeseong River rises in Daegak Mountain, Suan County, Hwanghae Province. It flows into the West Sea along the boundary between Baecheon County and Gaepung County. In the 4th century, the Yeseong River was a northern border of Baekje as well as a southern border of Goguryeo. As Goguryeo promoted a full scale policy of southward extension, Baekje fortified many places between the Yeseong River and the Imjin River. Samguk Sagi (Historical Record of the Three Kingdoms) records that Baekje’s fortified frontier, beginning at Cheongmok Pass, ranged from Palgon Fortress in the north to the sea in the west. Many sites of ancient fortresses along the frontier between Goguryeo and Baekje are under North Korea’s jurisdiction. Thus, their excavation may be promoted as a joint project by the two Koreas.
Since the arts of shipbuilding and navigation were not developed in ancient times, ancient voyages were composed mainly of coastwise navigation (which means to navigate in the vicinity of a coast) in contrast to offshore navigation at a distance from a coast. Passing through the Bay of Gyeonggi, ancient vessels could depart from the central part of the Korean peninsula, and arrive in China, Japan, and the southern part of the Korean peninsula. Thus, the Bay of Gyeonggi was considered as a point of strategic importance in political negotiation, economic exchange and military operation.
The Han River meets the Imjin River just before, and the Yeseong River just after, the Bay of Gyeonggi. The bay, specifically the northern coast of Ganghwa Island, was a hub of inland waterways in the central part of the peninsula. One state that controlled the coast could enter Seoul, Gimpo, Goyang, Paju, Gaegyeong, and Baecheon easily through the Han River, the Imjin River, and the Yeseong River. That coast has been defined as the Han River Estuary by the Armistice Agreement of the Korean War.
The strategic importance of the Han River Estuary was recognized as of high priority in the rivalry between Goguryeo and Baekje in the 4th century. Gwanmi Fortress, which was called Gakmi Fortress a little differently by the Stele of King Gwanggaeto, was a symbol of that strategic importance. The fortress was a bridgehead for advancing toward inlands and seas as well as for defending aggression from inlands and seas. Indeed Goguryeo’s capture of Baekje’s Gwanmi Fortress in 396 changed the course of the rivalry between the two kingdoms. According to Samguk Sagi, Gwanmi Fortress was a bluff surrounded by the seas and King Gwanggaeto attacked the fortress through seven different routes to take it in 20 days.
Kim Jeongho’s Daedong Jiji, which was written in the 19th century, records the Odu Mountain Fortress as Gwanmi Fortress. (Fig. 1) As the Imjin River meets the Han River in front of Odu Mountain Fortress, the site appears to be of strategic importance. Additionally, Odu Mountain Fortress matches the geographical shape of Gwanmi Fortress described by Samguk Sagi. However, Gwanmi Fortress was classified as an unidentified site even by Samguk Sagi, which was written in the 12th century. So, a sentence of Daedong Jiji cannot prove that Odu Mountain Fortress is the site of Gwanmi Fortress. According to several historical records that the Yeseong River was a border between Goguryeo and Baekje even after Goguryeo’s capture of Gwanmi Fortress, the likelihood of Odu being the site of Gwanmi Fortress is low.
The Haeum Mountain Fortress is another alleged site of Gwanmi Fortress. Haeum Mountain Fortress of Bongcheon Mountain in the northern part of Ganghwa Island is called the Bongdu Mountain Fortress or Bongcheon Mountain Fortress. Bongcheon Mountain is of strategic importance with wide visibility and various connections. Unlike the present Bongcheon Mountain, which is not surrounded by the seas, its ancient shape was similar to what Samguk Sagi described Gwanmi Fortress. Before the land reclamation project began in the 13th century, Ganghwa Island had irregular coastlines and was separated into several small islands.
The name of Gwanmi Pass can also be found in Samguk Sagi, which documents that at Gwanmi Pass, Baekje did battle with the Malgal whose home-ground was located in the eastern part of the Korean Peninsula. Ganghwa Island including Haeum Mountain Fortress was too far from the Malgal’s base and it was not plausible for the Malgal to arrive at Ganghwa Island going through many of Baekje’s impregnable fortresses. Small islands do not usually have a mountain pass. Thus, Haeum Mountain Fortress as a sort of small island may not be the site of Gwanmi Fortress.
Instead, a hilly mouth of the Yeseong River may be on the site of the Gwanmi Fortress. This is what has been inferred without any deep field investigation, which is impossible owing to military confrontation between the two Koreas. Though one specific area cannot be pointed to as the site of Gwanmi Fortress, it is obvious that the fortress was located at the Han River Estuary, as defined by the Armistice Agreement of the Korean War. Baekje’s attack on Pyeongyang, Goguryeo’s major town, cannot be found in the history after Goguryeo’s capture of Gwanmi Fortress. Baekje’s and Silla’s exchanges with China were frequently blocked by Goguryeo. These facts imply that the Bay of Gyeonggi was under the control of Goguryeo. Goguryeo’s capture of Gwanmi Fortress enabled Goguryeo to control the bay.
After several wars at Ganghwa Island with such major powers as Mongolia, France, the United States, and Japan, the Han River Estuary reemerged with the armistice of the Korean War. The Armistice Agreement of 1953 and its annex prescribe that the waters of the Han River Estuary should be demilitarized and open to civil shipping across both sides where one bank is controlled by one side and the other bank is controlled by the other side. The contact line between water and land at high tide has been made through the boundary line between the Han River Estuary Area and the area under the military control of either side. Civil shipping on each side is supposed to have unrestricted access to the land under the military control of that side. Furthermore, a ship, vessel, or craft from one side shall not have access to the waters or shore controlled by the other side, shall not go closer than one hundred metres to the boundary of the Han River Estuary Area on the other side, and shall not sail or operate during hours of darkness.
The Nadeul Island project has been criticized by some environmental groups as well as by North Korea. The key point of controversy over the Han River Estuary, including Nadeul Island, is of logistical matters in military-strategies, transport efficiency, and ecological balance.

Fig. 2  Southern Boundary of the DMZ across the Imjin River
The Imjin River as Border between Goguryeo and Silla
Gwangju Mountains are the closest of the Korean mountain chains to the Korean DMZ. Gwangju Mountains range from Geumgang Mountain to Seoul. The long valley closest to the DMZ is Chugaryeong Rift Valley, which is a valley between the Gwangju Mountains and the Masikryeong Mountains. The Gyeongwon Railroad from Seoul to Wonsan runs along Chugaryeong Rift Valley. The Masikryeong Mountains cover an area stretching from Mashikryong, where the North Korean government recently developed a ski resort, to Gaeseong.
The Imjin River rises from a south-facing slope in the Masikryeong Mountains while the Hantan River emerges at the north-facing slope of the Gwangju Mountains. (Fig. 2) The two rivers flow separately along Chugaryeong Rift Valley and meet at Jeongok. After the Hantan River flows into the Imjin River, the river flows westwards and meets with the Han River at the West Sea. Some banks of the Imjin/Hantan River are composed of cliffs with basalt columnar joints and are difficult to cross. Other riverbanks without cliffs had thick layers of sediment at the river bed and are easy to cross. The Imjin River is long but shallow compared to other long rivers in the peninsula. This shallow river makes many traffic routes possible, but it also let its own defense system more vulnerable to the rival’s offense. Thus, many fortresses were built to deter the crossing of the Imjin River.
As the Imjin River area is a major transportation point between North and South, it has been considered a strategically significant place in terms of military as well as traffic. Neighbouring states in ancient times engaged in heated competition for acquisition of the area. The Imjin River areas were occupied by Baekje first and by Goguryeo later. After Silla expanded its own domain to the central part of the Korean peninsula in the 6th century, the Imjin River worked as a border between Goguryeo and Silla.
Goguryeo’s fortresses along the Imjin River area were located on the riverbanks or inland along the mountains. The fortresses were connected along traffic routes in a north-south direction. A fortress was built at each ford that can be crossed with ease, and another fortress was built the opposite side of the river. There were three fortresses at three fords in which the Imjin River can be easily crossed: Horogoru Fortress, Dangpo Fortress, and Eundaeri Fortress.
First of all, Horogoru Fortress is located at the ford which can be first met upstream. (Fig. 4) Samguk Sagi represented this section of the Imjin River as Horoha (Horo River). In the ancient times, most of the best routes from Pyeongyang to Seoul went by Horogoru Fortress. Baekje’s and Silla’s styles of fortifications, as well as Goguryeo’s roof tiles, were discovered during the excavation of the site of the Horogoru Fortress. So, it may be inferred that the fortress was occupied at least once by each of the three kingdoms.
Horogoru Fortress was built on a deltoid plain of the riverbank. Among three faces of the fortress boundary, two cliffs respectively border the Imjin River and its branch. Ramparts were built on the other side which connects with the inland areas. This style of fortification can be discovered in the Imjin River area only. There are two more fortresses built on a deltoid plain: Dangpo Fortress and Eundaeri fortress. They are also located at a ford in which the river is shallow so that it can be easily crossed. This is because sediment deposits as a stream joins the Imjin River. These fortresses of deltoid style contributed to stabilizing borders on wide plains.
Samguk Sagi described the Imjin River as the Chiljungha (Chiljung River) which means a river that curves seven times. Near the Imjin River the site of fortress called the Chiljung Fortress can be found. (Fig. 3) It seems that the fortress was named Chijung Fortress as the fortress was built and operated as according to its relationship with the Imjin River.
When a northern force invaded southward or when a southern force invaded northward, it could cross a river in the central part of the Korean peninsula. The section of the Imjin River from Horogoru Fortress to Dangpo Fortress was one of the easiest to cross. Chiljung Fortress, surrounded by plains and downs, had some viewing points and therefore controlled the river areas. The fortress was of strategic importance with neighbouring fortresses built in every direction.
Efforts to capture Chiljung Fortress were frequently made as its strategic value was recognized. Since a fortress conqueror was replaced frequently in ancient times, relics of all the three states have been discovered in the fortress.
After Goguryeo collapsed, Chiljung Fortress was no longer a ferocious battlefield between Goguryeo and Silla. Silla and Tang waged many battles with each other after Baekje and Goguryeo collapsed in 660 and 668, respectively. The major battlefront between Silla and Tang was located on the Yeseong River before 672, in which Silla fell. Later, the battlefront moved to the Imjin River. Some Goguryeo refugees joined hands with Silla to expel Tang from the Korean peninsula. In 675, Silla was engaged in several fierce battles against Tang in the Imjin River area including Chiljung Fortress, and Silla finally won the war. As in 677 Tang moved its Andong Protectorate from Pyeongyang to Yodong, Silla ended its war of the unifying of the Korean peninsula.
Even during the Korean War from 1950 to 1953, the traditional invasion route crossing the Imjin River was taken again and the river became a major battlefront. In April of 1951, the Chinese Communist Field Army commanded by De-huai Peng arrived at the Imjin River in front of Jungseong Mountain (Chiljung Fortress Mountain). The Gloucestershire Regiment of the United Kingdom took some hills including Jungseong Mountain to defend China’s attack. The UK soldiers called the mountain Castle Hill, due to the fact that ‘seong’ of Jungseong means fortress or castle. With China’s huge attacks, a battalion of the Gloucestershire Regiment was almost annihilated in three days. However, it delayed Peng’s plan to advance toward Seoul. Thus, these fortresses worked effectively as a key base for UN forces to block the Chinese advance toward Seoul. The Imjin River was a border or a battlefront during the Korean War as it was in the ancient times.
Fig. 3 Chiljung Fortress near by Imjin River was constructed at Jungseong Mountain, Gueup-ri by masonry walls.

Today, the Imjin River is no longer a border between North and South. The river crosses the DMZ. Rivers that cross borders may provide a pretext for disputes. The upper state of a specific river can damage the lower state of the river by obstructing the flow of water, and the lower state can cause the upper state harm by submerging the upper region of the dam of the lower region. When it rains in North Korea, topsoil flows into the Imjin River and sediment is deposited in the river. As such, the Imjin River becomes so shallow that it may flood even with only little rain. In the summer of 2009, North Korea discharged water into the Imjin River without any notice and several South Korean civilians drowned.
Cooperation at the Imjin River is needed and it is more likely to be promoted when linked to the control of flooding, production of economic values, and preservation of ecological values.
A Spatio-History of the DMZ as a Network of Frontiers
About 47 sites of fortresses have been found in and around the DMZ area. Among them, 37 fortresses were built during the era of the Three Kingdoms. Most of those fortresses were discovered along the Imjin River., and more fortresses were found on its southern river bank than its northern bank. This means that the purpose of building the fortresses was mainly to defend invasion from the north.
The DMZ area, which divides the Korean peninsula, was the borderland and battlefront between the ancient Three Kingdoms that struggled for dominance over the peninsula, as well as the battlefront during the Korean War of the 20th century. It is not common for a fierce battlefront of modern wars to remain in a specific area for more than two years. Indeed the Korean War is the only modern war in which armistice has been kept without concluding its peace treaty for more than 60 years. A long armistice may be related to powerful allies of the Koreas. Most world powers of the 20th century as well as the 7th century participated in many battles around the DMZ area.
Many battles during the Korean War were fought for better logistical and strategic sites which enable their occupants to observe and deter their enemies. Key strategic bases were sought by the ancient Three Kingdoms as well as by North and South Korea. A strategic base may be considered to be a hub of networks, which is not necessary only for military logistics but also for industrial logistics and ecological networks. For instance, the UNESCO Biosphere Reserves are organized into three interrelated zones: the core zone, the buffer zone, and the transition zone. Frontier networking is a value inherent to the DMZ that transcends time.
Fig. 4  Horoguru Fortress is a triangle topography surrounded by Imjin River on the left and a stream on the right.

Jung Weonjoo got a doctorate in Korean history of the Graduate School of Korean Studies at the Academy of Korean Studies and is a lecturer in Kyungmin College. She wrote The Development and the Modification of the Birth Myth of Koguryo, A study on the Fall of Koguryo and etc.

Kim Chaehan (corresponding author) a professor at Hallym University, has a Ph.D. in political science from the University of Rochester. He was a National Fellow at Hoover Institution, and has been selected as a National Scholar by the ROK Ministry of Education. His research was supported by Hallym University Research Fund (HRF-201405-005).

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no.560 (2014.July) 
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