Shimookada Government Office Ruins

Shimo-okada Kanga Site: An Ancient Government Outpost on the Sanyō Highway

Tucked into a quiet residential corner of Fuchū Town, just east of Hiroshima City, lies an archaeological treasure that opens a window onto one of the most important transportation arteries of ancient Japan. The Shimo-okada Kanga Site (下岡田官衙遺跡) is the remains of a government facility from the Nara period (8th century), believed with very high probability to be the "Aki Umaya" (安芸駅家)—an official relay station on the Sanyō-dō, the great highway that linked the imperial capital of Nara (and later Heian-kyō) with the southwestern administrative center of Dazaifu in Kyūshū.

Designated a National Historic Site on March 26, 2021, this modest-looking site of just under 3,600 square meters preserves the footprint of an extraordinary chapter in Japanese state-building. Here, ancient bureaucrats once changed horses, took their meals, and rested for the night while travelling on government business across the wide territory of the early Japanese state.

Historical Background

In the late 7th and early 8th centuries, Japan was rapidly transforming itself into a centralized state modeled on Tang Dynasty China. As part of this great reorganization, the imperial government constructed seven major highways—the "Shichidō Ekiro" (七道駅路)—that radiated from the capital to the provinces. Of these seven, only one was designated as an "Ōji" (大路, great road): the Sanyō-dō, which carried the most critical traffic between the capital and Dazaifu, Japan's diplomatic gateway to the Asian continent.

Along this corridor, at fixed intervals of roughly thirty ri (about 16 kilometers), the government established post-stations called "umaya" (駅家). Each umaya kept a stable of horses, accommodations, and provisions, ready to serve travelling officials, military couriers, and government messengers. Aki Province alone contained thirteen such stations. The Shimo-okada site occupies a strategic position on the slope where Hiroshima Bay's hilly hinterland descends toward the coastal plain—a true crossroads of land and sea transport.

Archaeological work has revealed that the site went through three distinct phases. It first appeared in the late 7th century as a workshop connected with lacquer production. Around the middle of the 8th century, it was deliberately rebuilt as a formal government compound centered on two tile-roofed stone-foundation buildings. By the early 9th century, the facility had fallen into disuse and was abandoned.

Why It Was Designated a National Historic Site

The Shimo-okada Kanga Site earned its national designation for several interrelated reasons. First, it occupies a strategic location at a node of both land and maritime transportation along the Sanyō-dō, making it pivotal evidence for understanding how the ancient Japanese state projected its authority across distance. Second, the site has been the subject of systematic archaeological inquiry since the 1960s, and its long research history has given it a foundational role in Japanese transportation archaeology.

The reinvestigations carried out by Fuchū Town's Board of Education between 2016 and 2019 reexamined earlier finds and added new data. The scale of the buildings, the quality of the roof tiles, and the assemblage of recovered artifacts all point away from interpretations such as a temple, a provincial seat, or a county office, and toward the conclusion that this was almost certainly an "umaya"—a post-station. As one of the few umaya candidates whose physical form can actually be traced on the ground, the site is an essential reference point for understanding how government outposts evolved along the Sanyō corridor.

Highlights of the Site and Its Finds

The Tile-Roofed Stone-Foundation Buildings

Two substantial buildings stood at the heart of the 8th-century compound. They were built on large stone foundation pads (rather than on the simple pillar-in-pit technique used for most ordinary structures of the period) and crowned with tile roofs—a serious investment that signalled official, state-sponsored construction. The two buildings were arranged in an L-shaped configuration facing directly onto the ancient Sanyō highway, presenting an impressive façade to anyone passing along the road.

Roof Tiles and Wooden Tablets

Among the most significant artifacts unearthed at the site are roof tiles bearing the "jūken-mon" (concentric circle) pattern on the eave end-tiles. These share design features with tiles excavated at Aki Kokubunji (the provincial temple of Aki, in present-day Higashi-Hiroshima City), pointing to a coordinated state-sponsored tile production effort during the same period.

Even more revealing are the "mokkan" (木簡), thin wooden tablets used in ancient Japan for record-keeping and labelling. Mokkan recovered from Shimo-okada bear inscriptions including the place name "Takata-gun" (高田郡), a county in northern Aki Province, along with names of goods—silent testimony to the flow of administrative information and tribute along the highway.

Additional Finds

Excavations have also yielded earthenware (土師器 and 須恵器), green-glazed ceramics, inkstones, lid fragments from document boxes (文書函蓋), wooden ritual implements (斎串), ancient coins, and other items, painting a vivid picture of daily life at a working government outpost.

Visitor Information

An honest note for international visitors: the Shimo-okada Kanga Site, in its current state, asks the visitor to bring imagination along. After excavations were completed, the area was carefully reburied to protect the remains. Today the surface is occupied by privately owned fields and parking lots, and the site itself cannot be entered. An interpretive sign explains what once stood here.

For travelers who appreciate the quiet pleasure of standing where history happened, however, the site rewards a brief visit—especially when paired with a stop at the Fuchū Town Historical Folk Museum, where many of the actual finds from the site are on display. The museum brings the buried site back to life through artifacts, photographs, and explanatory panels.

Please note that the designated area is on private land. Visitors are kindly asked to remain on public roads, refrain from entering the marked zone, and be considerate of nearby residents, as the site sits within a quiet urban neighborhood.

Surrounding Attractions

Fuchū Town and its immediate surroundings offer a rich layer of historical sites that complement a visit to Shimo-okada beautifully.

Taga Shrine (多家神社) — Together with Itsukushima Shrine and Hayatani Shrine, Taga Shrine was historically counted as one of the three great shrines of Aki Province. Its treasured storehouse (神輿蔵), relocated here from Hiroshima Castle, is a designated Hiroshima Prefectural Important Cultural Property and a rare surviving example of the original buildings of Hiroshima Castle.

The Aki Kokuga Site (Tadokoro Myōjin Shrine area) — The site of the ancient Aki Provincial Government compound, now occupied by a shrine maintained by descendants of the Tadokoro family. The "Tadokoro Monjo," important medieval documents tracing land records, are preserved here.

Hiroshima City Center — Just a short train or tram ride from Fuchū lies Hiroshima itself, home to the Peace Memorial Park and Atomic Bomb Dome (UNESCO World Heritage), Hiroshima Castle, and the Shukkei-en garden.

Itsukushima Shrine on Miyajima Island — A UNESCO World Heritage site about 90 minutes away, famous for its floating torii gate and sweeping vermilion halls.

Aki Kokubunji Site (Higashi-Hiroshima) — The ruins of the Nara-period provincial temple of Aki, whose roof tiles share designs with those found at Shimo-okada. Together, the two sites help visualize the spread of state-sponsored construction across 8th-century Aki Province.