About This Proposal
Today, Japan is widely perceived as a fully established nation-state. However, in ancient times, the Japanese archipelago was still in the process of forming its political borders and systems of governance.
Amid tensions with Tang China and Silla, the expansion of control into the northern frontier inhabited by the Emishi, and increasing interaction within the East Asian world, the Ritsuryō state developed its political system by constructing fortified administrative centers, mountain castles, and provincial government offices.
These were not merely military installations. They formed an integrated network of administration, diplomacy, transportation, and defense that supported the emerging ancient state.
This proposal explores the process of state formation in the Japanese archipelago through these surviving fortresses and administrative sites.
Fortified administrative sites and ancient mountain castles stood at the front line of state formation in Japan
Interpretation of Value
1. Tensions with the Asian Continent
The Ritsuryō state of ancient Japan developed within a context of political and military tension with neighboring powers such as Tang China and Silla. Following the defeat at the Battle of Baekgang in 663, Japan accelerated the development of large-scale defensive systems across the archipelago.
Building to Defend the State
The beginning of Japan’s ancient defense network
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In the late 7th century, Japan suffered a major defeat at the Battle of Baekgang against the allied forces of Tang China and Silla. This event triggered a strong sense of crisis within the Yamato court.
As a result, a series of ancient mountain fortresses were rapidly constructed across western Japan, including Ōno Castle, Kii Castle, and Yashima Castle.
These fortresses show clear influences of continental East Asian fortification techniques. Stone walls, earthworks, and water-control structures reflect architectural knowledge associated with the Korean Peninsula, particularly Baekje traditions.
Dazaifu and Mizuki were not merely defensive structures, but strategic centers integrating diplomacy, military command, and administration.
Kaneda Castle on Tsushima Island functioned as a frontier stronghold closest to the Korean Peninsula, serving as the first line of defense for the Japanese archipelago.
These archaeological remains illustrate how Japan formed an organized defensive system within the wider geopolitical dynamics of East Asia.
2. Expansion of Northern Governance
In addition to strengthening defensive systems in western Japan, the Ritsuryō state also advanced its administrative control over northern regions of the archipelago. Across the Tōhoku region, fortified administrative centers (josaku) and government complexes were systematically established, forming a state-wide network that supported northern governance.
Expanding Northward
The frontier of the ancient state
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In the Tōhoku region, the Ritsuryō state constructed a series of fortified administrative centers and provincial government offices, gradually extending its control over the northern frontier.
Tagajō was established as the provincial capital of Mutsu Province and functioned as a central hub for military, administrative, and diplomatic affairs in northern Japan.
Isawa Castle was constructed as a strategic base for military campaigns led by General Sakanoue no Tamuramaro during the conquest of the Emishi. Beyond military operations, he also contributed to the development of administrative systems and the establishment of fortified settlements, laying the foundations of northern governance.
Sites such as Shiwa Castle and Tokutan Castle were also key nodes in this system, distributed along the Kitakami River basin. These sites functioned not only as military facilities but also as centers for administration, logistics, and transportation management.
In addition, Akita Castle and the Taga Stockade on the Sea of Japan side served as frontier bases supporting northern maritime control and international exchange, including contact with the Bohai Kingdom.
These fortifications demonstrate how continental fortification techniques were adapted to the geography of the Japanese archipelago. Their earthworks, spatial layouts, and administrative zoning reflect a highly planned system of state design characteristic of the Ritsuryō government.
Together, these archaeological sites provide important evidence of the expansion of Ritsuryō governance and the realities of northern frontier administration.
3. Influence on Ancient Culture
The expansion of governance and defense under the Ritsuryō state influenced not only politics and warfare but also Japanese culture itself. Fortified settlements and border checkpoints frequently appear in classical literature and historical chronicles.
Recorded Boundaries of the State
The stage of ancient culture
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The formation of the Ritsuryō state is recorded in historical chronicles such as the Nihon Shoki and Shoku Nihongi. The construction of fortified sites, frontier policies, and defensive systems were major state projects of ancient Japan.
Sites such as Tagajō and Akita Castle are among the few ancient state-related archaeological sites where historical texts and physical remains correspond directly.
The Shirakawa Barrier was known as a symbolic boundary to the eastern provinces and frequently appears in classical waka poetry and travel literature. It also played a key role in shaping the cultural perception of “Michinoku” (the northeastern region).
The Man’yōshū contains numerous poems related to frontier guards (sakimori) and the eastern regions, reflecting how borders and human migration became central themes in ancient literature.
Through these historical and literary sources, the memory of Ritsuryō boundaries and governance has been preserved as part of Japan’s cultural heritage.
Comparison with World Heritage Sites
By comparing with World Heritage Sites such as ancient capitals, frontier defense lines, and boundary-related heritage sites, the value of the “Fortified and Administrative Sites of the Ritsuryō State Period in Japan” becomes even clearer. Please click"" the images below to view the comparisons.
Common point: A unified system of capital, religion, and burial culture that supported the formation of an ancient state under a ritsuryō-style governance framework.
Difference: Gyeongju represents a centralized capital-based urban culture, whereas the Ritsuryō sites form a decentralized system focused on regional control and frontier administration.
Common point: A large-scale defensive and administrative network constructed along the frontier against northern nomadic peoples.
Difference: The Great Wall is a continuous linear fortification, whereas the Ritsuryō sites form a dispersed system of fortresses, government offices, and roads working together.
Common point: Frontier military installations built by an empire to manage boundaries with external peoples.
Difference: Hadrian’s Wall is a linear border defense structure, while the Ritsuryō sites form a wide-area administrative and military network.
Common point: A fortified site located at the boundary between civilizations, integrating military and administrative functions.
Difference: Derbent is a city-based defensive stronghold, whereas the Ritsuryō sites are a dispersed national governance network.
Next is a comparison with Japanese World Heritage Sites. Again, please click"" the images below to view the comparisons.
Common point: Represents the political, religious, and cultural integration of the Ritsuryō state during its formative period.
Difference: Nara was a centralized political capital, whereas the Ritsuryō sites function as a regional network of governance and frontier defense.
Common point: A national heritage site where state rituals are closely connected with maritime routes and diplomatic networks.
Difference: Okinoshima is a sacred maritime ritual site ensuring navigation safety, whereas the Ritsuryō sites form a land-based military and administrative system.
Existing World Heritage Sites generally represent either “centers” or “boundaries” used by ancient states to maintain order. In contrast, the “Fortified and Administrative Sites of the Ritsuryō State Period in Japan” are characterized not by a single city or continuous defensive wall, but by a dispersed system of fortresses, government offices, and transportation networks that supported national governance across a wide area. This heritage group illustrates a uniquely East Asian Ritsuryō-style structure in which both the “center” and the “frontier” of the state are simultaneously constructed.
Why This Selection?
Here, we will organize what meaning the “Fortified and Administrative Sites of the Ritsuryō State Period in Japan” hold within Japan’s historical context. The reasons can be summarized into three points. Please click"" the sections below to view the details.
This heritage group consists of archaeological remains that concretely demonstrate the formation process of the Ritsuryō state in the Japanese archipelago. It is characterized by a systematic distribution of capitals, provincial government offices, military bases, and frontier fortifications (jōsaku). These sites provide material evidence of the establishment of a centralized governing system in ancient Japan and play an important role in understanding state formation in domestic history.
The network of frontier fortifications represented by Tagajō, Akita Castle, and Isawa Castle functioned as key administrative and defensive bases in northern Japan. These were not merely military installations, but multifunctional centers integrating administration, diplomacy, and logistics. They provide concrete evidence of how the Ritsuryō state expanded and extended its system of domestic governance.
This heritage group is distinctive in that it corresponds directly with historical texts such as the Nihon Shoki and Shoku Nihongi, while also being physically verifiable as archaeological sites distributed across the country. The alignment between written sources and material remains enables a three-dimensional reconstruction of the Ritsuryō state in Japan. As such, it forms a systematic heritage ensemble that illuminates the reality of ancient governance.
In this way, the heritage group serves as a representative collection of archaeological sites that demonstrate the formation and governing structure of the Ritsuryō state in Japan. Its significance is supported both by historical documents and archaeological evidence, forming an important cultural foundation for understanding state formation in Japanese domestic history.
Components of the property
From here, we introduce the component heritage sites that form this proposal.
However, these are only representative examples and should not be regarded as the “definitive” selection.
Defensive Line against the Continent
Northern Administrative Bases
Criteria
Let us organize the values we have seen so far in relation to the UNESCO World Heritage “criteria”. The significance of the “Fortifications and Administrative Centers of Ritsuryō-Period Japan” becomes even clearer in this context.
Influence of Cultural Exchange
A governance system formed within East Asian inter-state networks
This property was formed under the influence of diplomatic, military, and cultural exchanges with East Asian states such as Tang, Silla, and Balhae. Dazaifu and the Kōrokan functioned as international contact points, demonstrating that the formation of the Ritsuryō state in the Japanese archipelago progressed through its relationship with the broader East Asian world.
Evidence of Historical Tradition
Material evidence of the Ritsuryō state consistent with written records
This property corresponds to descriptions of governance in historical chronicles such as the “Nihon Shoki” and the “Shoku Nihongi”. Archaeological remains of fortifications, administrative compounds, and defensive structures provide tangible evidence that the state system of ancient Japan was actively functioning.
Development of Architectural and Technological Systems
State infrastructure based on ancient East Asian fortification techniques
This property demonstrates the development of composite structures such as fortified settlements, mountain castles, and administrative compounds adapted to the Japanese archipelago, while incorporating fortification techniques influenced by the Korean Peninsula and the Asian continent. These are characterized not as isolated defensive structures, but as integrated national infrastructure combining administration, military functions, and logistics.
In Closing
Today, we live with the assumption that concepts such as “the state,” “administration,” “roads,” and “cities” have always existed as they are now.
However, in the ancient Japanese archipelago, these systems were still in the process of formation rather than being fully established. Amid external threats, trial-and-error approaches to regional governance, and relations with the wider East Asian world, the very shape of the state was gradually being built.
Mountain fortresses, fortified administrative centers, boundary barriers, and defensive lines—. These were not merely military facilities, but also expressions of the will of the people who sought to sustain the state itself.
By constructing earthworks, arranging wooden palisades, and developing administrative centers and road networks, the Ritsuryō state expanded its system of governance across the Japanese archipelago. The hardships faced by those managing these frontier regions may well have been no less severe than those of modern times.
The network of sites built through such efforts eventually formed the structural foundation of the Japanese state, becoming the basis for later systems of governance and urban development.
The fortifications and administrative institutions established by the state represent the very process through which ancient Japan formed the concept of “the state” itself. Rather than being mere archaeological remains, they can be regarded as “monuments of the ancient state” that preserve the memory of state formation in the Japanese archipelago.
A “World Heritage Site” like this—why not?
