A heavily fortified Yoshinogari settlement (Artwork: Nihonnoruutsu)
For Yayoi people, it was increasingly a time of conflict, turmoil and trouble. It was a time for the tightening of tribal ties and for evicting enemies.
Settlements and villages became larger over the Yayoi period. They became increasingly fortified. The Yayoi inhabitants built moats, embankments, ditches, wooden palisades and watch towers to protect their villages from hostile outsiders. The moats multiplied and were widened and deepened.
Mountain lookouts and settlements increasingly built on hillslopes and mountainsides were defensive arrangements indicating escalating tension and conflict. At Ogidani in Kyoto, there were two encircling ditches about 1 km long … the dirt moved to make the ditches would have filled a thousand 10-tonne dump trucks.
An oval moat encircled the settlement situated on a high terrace at Itasutsuke in Fukuoka prefecture. Water was supplied by a canal that ran along the edge of the terrace over the rice paddy, and the canal doubled as an outer moat. A dam had been built in the canal and an outlet beside the dam controlled water flow into the rice fields.
The hill-top settlement of Otsuka near present-day Yokohama was a strongly fortified bastion. Another example is the Santonai settlement on the bluffs of Yokohama Bay that once had a crowded Yayoi community (evidenced by the ancient traces of many overlapping pits) within its fortified village.
79 villages of the Yayoi era from Kyushu to northeastern Honshu were excavated during the post-war years, many large settlements located on plains as well as upland habitations, that were protected by ditches (kango shuraku). After the 3rd century AD they suddenly disappeared and the defensive systems were not seen again until after 1200.
At Asahi site in Aichi prefecture, there were 3 trenches, the outer one 5 to 7 metres deep enclosing 10 hectares. The second and third ditches were only 1.5 metres to 2 metres wide, but inside the trenches villagers had implanted stakes, planks and twisted branches that made access totheir homes exceedingly difficult. Further outside the last ditch was another line of thigh-high stakes and planks. The only way in and out of Asahi would have been bridge.
In Kyushu, Yoshinogari is by far, the largest and the most impressive of all the fortified settlements with many watchtowers, double ditch enclosures and many palisades (fencing with sharp stakes). In the Kinai (Osaka-Nara-Kyoto region), the large Karako-kagi settlement has impressive watchtowers as well.
Archaeologists say excavated finds such as swords, arrowheads and halberds indicate that conflict and warfare intensified. There was a stage during the Yayoi era when weapons were intensively produced, when metal weapons displaced stone ones, and when defensive villages were built especially from the eastern Inland Sea to the Kinki area.
Other discoveries of dismembered or wounded skeletons support this view. One skeleton at Doigahama had a stone arrowhead in its skull and a female skeleton at Nejiko, in Nagasaki had a bronze arrowhead in hers. Several skeletons at Yoshinogari site were headless.
In addition to archaeological evidence, Wajinden or the Chinese “Commentary on the People of Wa”, presumably based on eye-witness observations, recorded that the Yayoi people went to war. “Their weapons are spears, shields, and wooden bows made with short lower part and long upper part; and their bamboo arrows are sometimes tipped with iron or bone.”
Yayoi bronze relics are concentrated in two regions: bronze weapons in north Kyushu and as far as the middle Inland Sea: and bronze bells in the eastern Inland Sea and as far east as the southern Tokai. Because bronze objects overlap in the Inland Sea where both types of bronze objects can be found … historians believe this was the critical area where the Tsukushi tribes of the south and the Kinki tribes of the east clashed.
During the Yayoi period, Kibi was a kingdom with great influence that acted as a cultural bridge with the Korean peninsula. The Kibi region (known as Okayama prefecture today) sandwiched in between the two tribes of Tsukushi and Kinki controlled the supply and traffic of vital materials bound for the Kinki, so that Kinki tribal leaders tried to consolidate their position and expand their power by either negotiating with or defeating the Kibi tribes. An early emperor tried to control the Kibi area by intermarriage.
The origin of the Yayoi village defensive system is unknown, but is thought to be of continental origin: Chinese examples date from 5,000-3,000 BC but are rather remote to have inspired the Japanese ones, villages with ditches along the coasts of southern Korea are thought to have more likely inspired the Yayoi defensive systems.