The Yayoi period marks the transition from hunting-and-gathering societies in Japan to those with a settled agricultural lifestyle, coinciding with the introduction of bronze and iron.

The Yayoi period is the second major prehistoric age in Japan. The name derives from Yayoi-chō, a section of the University of Tokyo campus where the first pottery unique to the period was discovered in 1884. The Yayoi is traditionally dated from 300 b.c.e. to 300 c.e., and was preceded by the Jōmon period (c. 10,000-c. 300 b.c.e.), which was marked by a hunting-and-gathering style of life. During the Yayoi, bronze and iron usage appeared for the first time, wet-rice cultivation was introduced, the population increased dramatically, and social and political organization began to emerge.

The period is broken up into three divisions. The Early Yayoi (c. 300-100 b.c.e.), centered in northern Kyūshū, represented a transitional phase during which the population adopted a mixed economy of rice cultivation and hunting and gathering. Evidence indicates that shellfish, a staple of the Jōmon diet, was still an important source of protein. Simple political divisions began to emerge at this time, with the settlements, most located in low, marshy areas, being ruled by a variety of chieftains.

The Middle Yayoi (c. 100 b.c.e.-100 c.e.) witnessed the development of water control systems for irrigation, the movement of settlements onto higher ground purposefully cleared, and the use of a variety of new tools, including many tipped with or made entirely of iron. Evidence indicates that the culture had spread as far north as present-day Nara.

During the Late Yayoi (c. 100-300 c.e.), irrigated wet-rice cultivation was perfected, complex political units began to emerge, and the culture extended to the northernmost reaches of Honshū. As Hokkaidō is too cold for growing rice, Yayoi culture never affected the far north of the Japanese archipelago.

The two most important advances of the Yayoi period are the introduction of wet-rice cultivation and the simultaneous entrance into the Bronze and Iron Ages. It is most likely that wet-rice technology was introduced into northern Kyūshū from the late Bronze Age culture in Korea. Trade was widespread, and evidence of significant contact between the Koreans and Jōmon Japanese is abundant. As noted above, the initial stages of settlement centered on low, marshy regions, where the inhabitants could take advantage of the natural irrigation, flooding, and accessible water tables. Diked fields and drainage systems allowed for ideal conditions to grow rice. Cultivation at this stage was simplistic, with hoes, spades, and reaping knives made of wood and stone. In the transitional stage, the basic diet was supplemented by hunting, gathering, and fishing. Even at an early period, however, communities were beginning to form around the new agricultural centers, with one of the oldest sites, in Itazuke, Fukuoka, boasting at least thirty homes.

As technology advanced in the Middle Yayoi, elaborate irrigation systems were developed and iron-tipped tools introduced. Paddy cultivation became a large-scale enterprise in some communities. Excavations at Toro, in present-day Shizuoka, reveal the technology and lifestyle of a Middle Yayoi community, which had a highly developed rice cultivation system, with more than fifty paddies covering seventeen acres. Supplied by sluice-gated irrigation ditches, the paddies sloped south, with residences and a storehouse located to the north. The paddies were separated by carefully cut wooden slats, presumably cut with iron tools. As production rose, storehouses were constructed with uniform planks for the flooring and walls, and the whole structure was raised 3 to 6 feet (1 to 2 meters) above ground, with wooden collars on each of the six posts to keep rodents out.

The homes, referred to as pit houses, were typically built with semi-subterranean floors, generally 1.7 feet (0.6 meter) below the surface. The pits were oval, with a cone-shaped superstructure built of poles and topped with a thatched roof of reeds or bark. The single-room dwellings typically had a central fireplace, with the interior banked with earth, creating a bench that supported wooden planks. The average home measured 19 by 26 feet (3 by 8 meters). Inhabitants wove cloth from flax and paper-mulberry fibers, and evidence suggests that men wrapped lengths of cloth around their bodies, while women slit a single piece and slipped it over their heads. Jewelry was manufactured, with jasper and jade beads strung together into necklaces and bracelets and occasionally made into rings.

The early Yayoi depended on a variety of wooden and stone tools. Typical implements included wooden rakes and shovels, fire drills, looms, and lathed bowls and cups. Some furniture was produced, and rice paddy clogs, known as geta, were used when transplanting rice. Stone tools became increasingly sophisticated, the axes and adzes growing larger and more highly polished, and were increasingly used for reaping rice, chopping, and tilling.

By the middle and late periods, iron and bronze had entered Japan. As was so often the case, bronze was primarily used by the upper class, both as a status symbol and for weapons, while the lower classes used iron to fashion tools and weapons. Bronze arrowheads may have been introduced as early as the second century b.c.e., with other weapons such as halberds, daggers, and short swords appearing in Kyūshū by the first century b.c.e. Local production in sandstone molds began in northern Kyūshū and around the Inland Sea, although quality was uneven for at least a century. As a symbol of wealth and power, the majority of bronze manufactures were mirrors, bracelets, coins, vessels, shield ornaments, and bells. A large number of bells have been uncovered, and it appears as though the Kinki region may have dominated this particular market. Bells throughout Japan were manufactured from the same mold and identified with the Kinki region. The majority appear to be ritualistic in nature; a number of sites have been uncovered in which several bells are buried in hillside terraces overlooking fertile fields. The reasons behind the burials are still shrouded in mystery, but many scholars speculate that they served in some type of ritual to ensure a good harvest.

At the same time, small-scale iron smelting produced a variety of implements and weapons. By the late Yayoi, iron was being used to fashion farming implements such as plows, sickles, and hoes; iron axes, chisels, and planes allowed for more sophisticated woodworking; and arrowheads, swords, and halberds, along with spearheads and fishhooks, were also forged. As noted, these tools allowed the inhabitants to move out of the marshy lowlands to comparatively dry land, where the soil was better suited to rice cultivation. The ability to clear forests and construct elaborate paddy field systems paved the way for very labor-intensive rice cultivation, which in turn produced larger and larger harvests. Because rice has more calories per unit than other farm products produced at the time, it was able to support a much greater population. Although exact numbers are unknown, some speculate that the population grew from an estimated 250,000 in Jōmon to 600,000 in the Middle Yayoi, and perhaps as many as 2.5 million by 300 c.e.

The growing population and emergence of agricultural villages naturally led to the development of social and political organizations. According to the Wei Zhi (written between 280 and 297 c.e.; “The History of the Wei Kingdom,” 1951), a Chinese history that provides the best glimpse of Yayoi society, Japan had become a highly stratified society by the third century c.e., with wealthy landowners ruling commoners. It also refers to Yamatai, a kingdom ruled by the shamaness Queen Himiko, that controlled more than thirty countries (kuni), each with their own chieftain. Within this kingdom, taxes were collected, marketplaces served as the center of trade, and class distinctions were rigidly enforced. When passing a member of the upper class on the road, commoners were required to retire to the roadside and kneel to show their respect. Although commoners had only one wife, the nobility were allowed four or five.

The Yayoi period marks a watershed in Japanese history. The Japanese transitioned from hunting and gathering to settled agricultural communities with highly structured and complex social organization and began to establish the foundations for the political, economic, and military specialization that would follow in the Kofun period (c. 300-710 c.e.).

The origins of Yayoi culture remain under study. Older theories proposing massive immigration from mainland China that overwhelmed and replaced the Jōmon have largely been abandoned. Consensus now holds that some immigration certainly took place during this period. Refugees and traders from Manchuria and Korea, along with immigrants from the Yangtze River region, undoubtedly brought the already developed technology of iron smelting and wet-rice cultivation. However, there is no evidence to suggest a wholesale replacement of the indigenous population with mainland immigrants.

The most likely scenario involves a degree of intermarriage between the Jōmon and immigrants, especially in western Japan, where the Yayoi are on average taller. In eastern Japan, the Jōmon simply adopted the new cultural elements. For example, the use of storage pits was developed in north China as early as 4000 b.c.e., and it is clear that the Yayoi imitated the production of such items as bronze mirrors and weapons, iron tools and weapons, and the building of wooden houses on posts, prominent in south China. Once adopted, however, these techniques and technology helped turn the Japanese archipelago into a flourishing and complex society.

• Barnes, Gina L. Protohistoric Yamato: Archaeology of the First Japanese State. Ann Arbor: University of Michigan, Center for Japanese Studies and the Museum of Anthropology, 1988. A seminal work dealing with the process and results of archaeological work for the Yayoi period. An extensive bibliography provides an abundance of additional resources.
• Hall, John Whitney, Marius B. Jansen, et al., eds. Ancient Japan. Vol. 1 in The Cambridge History of Japan. Cambridge, England: Cambridge University Press, 1993. A standard history of the period, placed into the context of Japan’s earliest societies.
• Imamura, Keiji. “Jomon and Yayoi: The Transition to Agriculture in Japanese Prehistory.” In The Origins and Spread of Agriculture and Pastoralism in Eurasia, edited by David R. Harris. Washington, D.C.: Smithsonian Institution Press, 1996. An excellent analysis of the climatic and sociological factors that combined to produce an agricultural society in Kyūshū.
• Kanaseki, H., and M. Sahara. “The Yayoi Period.” Asian Perspectives 19 (1979): 15-26. Very good overview of the cultural and material aspects of the Yayoi period.