北部九州と弥生の国々Northern Kyushu and the Yayoi Kingdoms

Today I am traveling across northern Kyushu, moving from Hakata to Itoshima, Karatsu, Takashima, and Saga. These are modern city and town names, but their roots trace back to the Yayoi period. For example, Itoshima was called Ito-koku (伊都国), and Karatsu was known as Matsuro-koku (末盧国). These names were recorded in the Chinese chronicle Wajinden (魏志倭人伝), the oldest historical source on Japan, where they are mentioned as part of the confederation of countries under the rule of the queen Himiko, who governed the polity of Yamatai. In fact, the Genkai Sea area of northern Kyushu symbolizes the complexity of the Japanese archipelago, which had experienced countless waves of migration long before the historical period, leaving behind traces that remain in the region to this day.

However, the greatest question raised by the Wajinden concerns the actual location of Yamatai, the kingdom ruled by the Yayoi-period queen Himiko described by the Wei envoys. Theories have long been divided between the Kyushu hypothesis and the Kinai (Nara basin) hypothesis, and the debate has continued for a very long time, growing more complicated each year with no end in sight. One of the most important pieces of evidence for the Kyushu theory is Ito-koku, which corresponds to present-day Itoshima.

Countless important Yayoi-period archaeological sites have been discovered in this region, and Chinese chronicles confirm that Ito-koku was treated as exceptional compared to other regions. Given that its scale was larger than neighboring countries, debates have arisen that Ito-koku was in fact the central kingdom at the time. Realistically, for people arriving in Japan from China or the Korean Peninsula, passing through Itoshima as the first gateway was natural, and thus Itoshima functioned as the front line of diplomacy. It controlled foreign information, goods, and people at the outset and expanded its sphere of influence through strong diplomatic ties across Japan.

Among the many sites, the most noteworthy is the Hirabaru site. This site is the burial ground of the last king of Ito-koku and has long been traditionally regarded as the tomb of Ohirume (大日孁命). The Kyushu theory of Yamatai identifies Ohirume with Himiko, and moreover, since Ohirume is described in the Nihon Shoki as another name for the ancestral deity Amaterasu, it suggests the involvement of influential immigrant clans who introduced Amaterasu worship.

Between Ito-koku (Itoshima) and Matsuro-koku (Karatsu), traces of some of the earliest rice paddy cultivation, farming tools, and enigmatic keyhole-shaped tombs (前方後円墳) remain in great numbers. Many gifts and trade goods from the Korean Peninsula and Chinese emperors have been excavated from these tombs, but what is remarkable is that the Hirabaru site even contains treasures granted only to close nobles of the Chinese emperor. This indicates that Ito-koku was effectively regarded as a noble directly subordinate to the emperor of China, privileged as the forward base controlling the unknown power of the Japanese archipelago.

Northern Kyushu developed greatly around this kingdom, but its strongly mixed culture with outsiders still remains visible in place names and customs, giving the region a faint sense of ancient foreignness even while traveling today. Many place names are particularly mysterious, to the point where one loses track of where one is journeying. The sounds of these names also share elements with Okinawa’s Ryukyuan language and older southern languages, which are thought to be traces of immigrant speech belonging to the Proto-Japonic (ancient Japanese-Ryukyuan) language brought by the Yayoi people with roots in Northeast Asia. Yet northern Kyushu was not a unified sphere but divided into separate cultural zones, observable even in differences between circular and rectangular pit dwellings in settlements.

Even in later times, northern Kyushu consistently served as the front line for people and armies arriving across the sea. Conversely, it also became the staging ground for Japanese expeditions to the Korean Peninsula. Seen as waves arriving across the sea, the first great influx was the large-scale migration from Northeast Asia during the Kofun period, which helped shape early Japanese statehood, but the most dramatic shock came later with the Mongol invasions.

Genghis Khan, the founding emperor of the Mongol Empire, expanded its dominion across East Asia, conquering China and Goryeo. Yet after his death, his sons broke the Mongol custom of youngest-son succession, seizing power independently and fiercely clashing over imperial inheritance. Internal rebellion rose, and their wars against the Southern Song and Goryeo were also plagued by strong local resistance. Kublai Khan, the fifth emperor, decided to invade Japan in order to redirect public dissatisfaction.

The Mongols, advancing with unstoppable momentum, underestimated Japan—of which they knew little—believing conquest would be easy. They sent envoys demanding Japan’s surrender through written orders. However, since Japan at the time had close ties with the Southern Song, many Song immigrants resided there, and the court was well informed about how far the Mongol Empire had expanded. Thus Japan firmly rejected their demands. Kublai resolved to invade, despite his empire already embroiled in multiple wars, and dispatched armies to Japan—an act that would prove the decisive trigger of the Mongol Empire’s collapse.

The Mongols first raided Tsushima and Iki, Japanese islands near the Korean Peninsula, leaving deep wounds on the islands, where many lives were lost and women were carried off, before attempting to land on Kyushu. Yet their miscalculation was that by then Japan’s ineffective aristocratic regime had already been replaced by a military government, and battle-hardened warriors were at their peak. The Mongols invaded twice: in 1274, Japan’s Kamakura shogunate narrowly repelled the first invasion, afterward building defensive walls along the northern Kyushu coast and strengthening samurai bands in preparation for another assault.

In 1281, during the second invasion, Mongol forces again attacked via Tsushima and Iki, pressing toward Hakata and Yamaguchi. Hakata became a battlefield engulfed in flames, with corpses strewn everywhere. But fierce resistance by warrior bands gathered from across Kyushu forced the Mongol troops to retreat to Matsuura Bay in western Genkai Sea, where they regrouped to await reinforcements. At this point, the small island of Takashima, which I am visiting today, became their attempted foothold.

However, the Matsuura navy, a skilled maritime force stationed across Takashima and Matsuura, harassed the Mongols with constant night raids and ambushes. Despite their smaller fleets, they outmaneuvered the Yuan forces and reversed the tide of battle. As the Mongols attempted further retreat, a typhoon struck the area directly—something highly unusual—and annihilated their fleet. Soldiers conscripted from China and Goryeo were nearly all killed, and in Japan the storm was revered as kamikaze (神風), the divine wind by which the gods protected Japan.

Thus Japan decisively crushed the advancing Mongol Empire, securing a victory recorded in history. Still, Japan suffered enormous losses, and with the fall of the Southern Song—conquered and destroyed by the Mongols—Japan also entered a new cultural era, adopting influences such as Zen, tea culture, and ink painting.

In the last three decades, many shipwrecks and weapons related to the Mongol invasions have been recovered from the seabed near Genkai Sea and Takashima, with research still ongoing. Looking out over the calm Matsuura Bay today, one might think the tragic war is buried beneath the waves, but considering the long history of northern Kyushu, the lives and memories of those who lived here may still carry faint traces of contact with the Mongol Empire to this very day.