Running through ancient times: Yoshinogari and Saga ~ JUL,2025 ~

I was worried about the rainy season weather while arranging tickets and accommodation for Saga, but before I knew it, the dry rainy season ended and my worries were unfounded. Under the scorching sun of over 38 degrees（℃） every day, I wandered around the Saga Plains, starting with the Yoshinogari ruins, and this is a place that Japanese history buffs drool over, with traces of ancient, medieval, modern and early modern times overlapping one another. At night, I explored　restaurants in search of Saga beef and Yobuko squid, and was very satisfied. On the other hand, despite having a rich and diverse tourist resource, the number of visitors was sparse (which was comfortable for me), and I got the impression that neither Saga City nor Saga Prefecture had narrowed down the target customer base or tastes. Of course, you might say that there are no people walking around looking at ancient tombs and shrines in this heat.

20,000 years ago, when the earth was last cold, Japan and the continent were almost connected by land, and the Tsushima Strait was almost closed, but since then, global warming has progressed, and 6,000 years ago, more than half of the Saga Plain was below sea level due to the Jomon Sea Level Rise. The Tomyo ruins, which were in an inlet at that time, were the remains of a residence that continued for about 700 years 8,000 years ago, when the sea level rose, and were subsequently abandoned due to rising sea levels. Thirty years ago, during construction of a flood control reservoir, a huge shell mound and relics were unearthed after digging 5m underground, and are said to be the largest in Asia.

At the same time, the Kikai Caldera, which caused a large explosion in the sea south of Kyushu, is located north of the Tokara Islands, where volcanic earthquakes are currently frequent, and the large amount of ash that fell at that time left Jomon villages in southern Kyushu uninhabited. This site is known as a "marsh shell mound," and after being submerged for a long time due to a sea level rise, clay deposits accumulated, and the calcium excavated from the shell mound neutralized the soil, preventing the decay and dissolution of many of the remains, allowing them to remain in their original form.

Yoshinogari is famous as a Yayoi period ruin from around the 5th century BC, but it is located about 7km east of the Tomyo ruins, and the continuity between them is intriguing. This ruin is famous for the large moated settlement that was built, which suggests the presence of external enemies, wars, and a king who was in charge of rituals, and is reminiscent of the turmoil in Wakoku and the existence of Yamataikoku and its neighboring countries.

Saga has a legend of Jofuku from the 3rd century BC. Jofuku was ordered by the First Emperor of Qin to lead an expedition to Japan with 3,000 young men and women and engineers in search of the elixir of life from the East. They landed on the coast of Morotomi in present-day Saga City, and a juniper tree brought by Jofuku is planted in the grounds of the Nikita Shrine. Naturally, this tree is 2,200 years old.

Sima Qian wrote in the Records of the Grand Historian that Jofuku did not return to Qin but became king there, and it would be interesting if there was a connection with the king of Yoshinogari. The Jofuku legend is found in Kumano, Kyoto and other places, but considering the route Jofuku set out from the Yellow Sea coast at that time, it makes sense that he mainly traveled along the Korean Peninsula or directly rode the ocean currents towards Nagasaki, so there is nothing strange about the Saga Jofuku legend that he invaded from the Genkai Sea or Ariake Sea.

Since moated settlements were also castles where defense was emphasized, the Yoshinogari ruins are registered as one of Japan's 100 most famous castles.

The Kase River, which flows from the Sefuri Mountains that run east to west through Saga Prefecture, and the Chikugo River, which flows in from the east, carried large amounts of sediment, causing sedimentation in the Saga Plain. After the Yayoi period, the land gradually expanded southwards, and what is now a vast rural area is now a network of rivers and countless creeks (irrigation channels for agriculture). Many of these were developed by the Saga Domain, contributing to the rice harvest, but the ground is extremely soft, and so when Saga Castle was built, boat-shaped timber was laid at the bottom and the stone walls were piled up to prevent the stones from sinking. The wetlands and creeks would have also been useful in defending the castle town.

Ancient ruins, including Yoshinogari, are scattered along the northern foothills, where the Nagasaki Road currently runs. Yoshinogari is home to a royal tomb called the North Burial Mound, where successive kings were buried in jar coffins, and many bronze swords, suga jewels, and silk have been excavated from the site. Next to the rectangular burial mound, which seems to foreshadow the arrival of the Kofun period, stand towering pillars reminiscent of the onbashira pillars of Suwa Taisha Shrine, and if you look up from there towards the royal palace, you can see Mount Unzen in the distance. It makes you wonder what became of the ancient kingdom afterwards. 

One possibility is Choshizuka Tomb, located at the foot of a mountain about 8km to the west. It is a keyhole-shaped tomb just under 100m long with its surrounding moat still in good condition and is estimated to have been built at the end of the 4th century. In Yame City, Fukuoka Prefecture, 30km from here, there is a group of tombs thought to be the tombs of the Iwai clan (Tsukushi no Kuni no Miyatsuko), among which is the tomb of a chieftain who rebelled against Emperor Keitai and was suppressed, also a keyhole-shaped tomb with a total length of 135m. This is the largest tomb in Kyushu, and it can be imagined that the person buried in Choshizuka Tomb was of comparable strength.

If you go west from Choshizuka Tomb and cross the Saga Yamato Interchange, you will see the Funazuka Tomb from the mid-5th century. It is a 115m long keyhole-shaped tomb, larger than Choshizuka Tomb, and it is thought that the area was ruled by a powerful person with connections to the Yamato Imperial Court.

Between the two burial mounds are ruins (the provincial office, provincial temple, and Hizen no Ichinomiya) that indicate the political and cultural center of Hizen Province. During the Nara period, Kibi no Makibi, who had traveled to China as a Japanese envoy, was appointed as the provincial governor. Hizen was a large province that included what are now Nagasaki and Saga prefectures, but in the Heian period, manors were widely established in the Saga prefecture area, causing the provincial government territory to shrink, and the provincial office seems to have essentially ceased to function during the 9th century.

Yoshihime Shrine, which is said to have been built in the reign of Emperor Kinmei (mid-6th century), and Daiganji Temple, which was abandoned in the early Heian period, are both located in the political center of the time. The torii gates of Saga shrines are called "Hizen torii" and have a short, slightly chunky top beam at the top. The Kase River flows beside the shrine, and the Saga domain brought water from this river into the castle and castle town. Until 1or2 thousands years ago, the southern part of the Saga Plain was the sea and tidal flats, and it seems that groundwater could not be used for drinking purposes.

A shrine is currently located at the site of Daiganji Temple, but many tiles and foundation stones from the Nara period have been discovered. The Nihon Ryōiki records that Saga no Kimi Kokimi, the governor of Saga, performed Buddhist rites. The neighboring ancient tombs may have been built by the ancestors of the Saga clan. There was a Buddha statue on display, the appearance of which was unclear, perhaps due to rain, wind, or fire, and I was fascinated for a while.

In the Kamakura period, the area was settled by vassals sent from Kamakura as shugo (military governor) and jito (local lord). It began with the appointment of shugo (military governor) by Yoritomo, and vassals moved here following the Jōkyū War and the Mongol Invasions, and became a fierce battleground during the Nanboku-chō period. The Chiba clan, relatives of the Sōma clan mentioned previously, built a castle here, and their descendants became vassals of the Nabeshima clan. The Shōni clan and their descendants, the Nabeshima clan and the Ryuzōji clan, also originated as vassals, and many Sengoku fans will be thrilled by the stories of the battle between Otomo Sorin and Ryuzōji Takanobu during the Sengoku period, and the invasion of the Shimazu clan. The small park on the south side of Saga Castle is the site of the former Mizugae Castle, and Ryuzōji Takanobu's umbilical cord is buried here.

Saga has always appeared at turning points in history, not only in ancient times but also since the Middle Ages, through the Northern and Southern Courts and Warring States periods, the Nabeshima clan government in the Edo period, its contribution to the Meiji Restoration as a powerful clan, the Seinan War and the Saga Rebellion. This time, I visited remains from the Middle Ages and early modern times, but I will cover the interesting stories in a separate article. I will end this article by writing about Eisai's tea, which was brought to Song China at the end of the Heian period. Deep in the mountains of the Sefuri mountain range, I visited the ruins of Reisenji Temple. The temple was abandoned during the Meiji Restoration, but one hall called Otogohodo remains, and I was able to visit it.

Eisai brought tea leaves with him when he returned from Song. When he stayed at Reisenji Temple, he cultivated tea on the slopes of a mountain, which is said to be the first tea cultivation in Japan. Saga is famous for Ureshino tea, which was brought to Japan by a Ming potter in the early 16th century. I managed to avoid the question by talking about tea.