The new Yayoi culture that arose in Kyushu, while the Jōmon culture was still undergoing development elsewhere, spread gradually eastward, overwhelming the Jōmon culture as it went, until it reached the northern districts of Honshu (the largest island of Japan). The name Yayoi derives from the name of the district in Tokyo where, in 1884, the unearthing of pottery of this type first drew the attention of scholars. Yayoi pottery was fired at higher temperatures than Jōmon pottery and was turned on wheels. It is distinguished partly by this marked advance in technique and partly by an absence of the proliferating decoration that characterized Jōmon pottery. It developed, in short, as pottery for practical use. It is accompanied by metal objects and is associated with the wet (i.e., irrigated) cultivation of rice, thought to have begun around the end of the Late Jōmon period. Culturally, the Yayoi represents a notable advance over the Jōmon period and is believed to have lasted for some five or six centuries, from about the 3rd century bce to the 2nd or 3rd century ce.

In China the 3rd and 2nd centuries bce correspond with the period of the unified empire under the Qin (221–207 bce) and Han (206 bce–220 ce) dynasties, which already had entered the Iron Age. In 108 bce the armies of the emperor Wudi occupied Manchuria and the northern part of the Korean peninsula, where they established Lelang (Nangnang) and three other colonies. These colonies served as a base for a strong influx of Chinese culture into Korea, whence, in turn, it spread to Japan. The fact that Yayoi culture had iron implements from the outset, and bronze implements somewhat later, probably indicates borrowings from Han culture. Since iron rusts easily, comparatively few objects have been found, but they seem to have been widespread at the time. These include axes, knives, sickles and hoes, arrowheads, and swords. The bronze objects are also varied, including halberds, swords, spears, taku (bell-shaped devotional objects from China), and mirrors. The halberds, swords, and spears seem not to have been used in Japan for the practical purposes for which they were developed in China but rather to have been prized as precious objects.

The cultivation of rice, probably introduced from the Yangtze River delta area of southern China, was one of the most important features of Yayoi culture. The earliest Yayoi pottery and sites, discovered in northern Kyushu, have yielded marks of rice husks as well as carbonized grains of rice; this suggests that rice growing was carried on in Japan from the earliest days of the culture. Traces of paddy fields, their divisions marked with wooden piles, have been found close to sites of settlements in various districts, along with irrigation channels equipped with dams and underdrains, showing that techniques of making and maintaining paddy fields were quite advanced. Rice was first grown in dry (i.e., nonirrigated) fields and marshy areas, however, before paddy cultivation—involving considerable investment of time, labor, and capital—came to predominate.

Generally speaking, the settlements of this period were built on low-lying alluvial land to facilitate the irrigation of the paddies, but at one stage they were built instead in the hills or on high ground. It is not clear whether this was dictated by the needs of defense or whether dry cultivation was being practiced. Much as in the Jōmon period, there were two types of dwelling—the pit type and the type built on the surface—but in addition to these, raised-floor structures appeared and were used for storing grain out of the reach of rodents.

With the acquisition of a knowledge of textiles, clothing made great strides compared with the Jōmon period. The cloth was woven on primitive looms, using vegetable fibers.

The dead were buried in either large clay urns or heavy stone coffins. Both were common in northern Kyushu and neighboring areas; similar urns and coffins also are found on the Korean peninsula, where they probably originated. The graves were usually marked by mounds of earth or circles of stones, but a special type of grave employed a dolmen (a large slab of stone supported over the grave by a number of smaller stones). Since the erection of dolmens was widely practiced in Manchuria and Korea, these too are believed to be a sign of an influx of continental culture. Normally, graves occur in clusters, but occasionally one is found apart, surrounded by a ditch and with swords, beads, and mirrors buried along with the dead. Such special graves suggest that society was already divided into classes.

While these new cultural elements represent a migration to Japan from the Korean peninsula or China, the migration was not of a magnitude to change the character of the people who had inhabited the islands from Jōmon times. Yayoi culture undoubtedly represents an admixture of new sanguineous elements, but it seems likely that the chief strain of proto-Japanese found throughout the country during the Jōmon period was not disrupted but was carried over into later ages. Differences in Jōmon and Yayoi skeletal remains can better be explained by nutritional than genetic reasons. This point of view is supported by the accounts of the “people of Wo,” found in the Chinese history Wei zhi (297 ce).

Chinese chronicles

Japan first appears in Chinese chronicles under the name of Wo (in Japanese, Wa). The Han histories relate that “in the seas off Lelang lie the people of Wo, who are divided into more than 100 states, and who bring tribute at fixed intervals.” Lelang was one of the Han colonies established in the Korean peninsula. A history of the Dong (Eastern) Han (25–220 ce) records that in 57 ce the “state of Nu in Wo” sent emissaries to the Dong Han court and that the emperor gave them a gold seal. The “state of Nu,” located on what is now Hakata Bay, in Kyushu, was one of the more than 100 states that constituted Wo. This account was confirmed by a gold seal, apparently the identical seal awarded by the Chinese emperor, unearthed on the island of Shikano, at the mouth of Hakata Bay, in 1748. In the latter half of the 2nd century, there was civil war in the state of Wo; Queen Himiko had pacified the land and, relying on her religious powers, ruled over a confederation of more than 30 states that maintained communications with the Wei kingdom (220–265/266) in northern China. Wei too sent emissaries to Wo, and friendly relations between the two sides continued during the first half of the 3rd century. The Wei zhi contains a detailed account of the route from Lelang to the court of the Wo queen in “Yamatai.”

Scholars are divided as to whether Yamatai was located in northern Kyushu or in the Kinai district (central Honshu). If it was in northern Kyushu, then the union of states was a purely local government, unrelated to the Yamato court of later times, but if it was in the Kinai district, then it would be natural to see it as the ancestor of that court. This would suggest, in turn, that Japan had already achieved a considerable degree of political unification. Japanese historians long sought to emphasize the antiquity and degree of unity of Yamatai in order to aggrandize Japan’s relations with other East Asian nations. It seems most likely, however, that Yamatai was a local center of power in Kyushu and that further unification did not take place until at least a century later.

According to the Wei zhi, the people of Wo already had reached a fairly high degree of civilization. Society had clear-cut divisions of rank, and the people paid taxes. There were impressive raised-floor buildings. The various provinces held fairs where goods were bartered. Since there were exchanges of letters with Wo, it seems too that there were already some who could read and write.

The unification of the nation

The questions of how the unification of Japan was first achieved and of how the Yamato court, with the tennō (“emperor of heaven”) at its center, came into being in central Honshu have inspired many hypotheses, none of which has so far proved entirely convincing. With the help of Chinese and Korean records, however, it is possible to get at least an approximate idea of the date by which substantial unification had occurred. The relations that Yamatai had begun with Wei were continued with the successor Jin dynasty (265–316/317); however, following the dispatch of a mission in 266, all records of exchanges cease, and it is not until 147 years later, in 413 during the Dong (Eastern) Jin dynasty (317–420), that the name of Wo again appears in Chinese documents. It is most likely that the blank period resulted from conditions within Japan that made exchanges with other countries impossible. The collapse of Yamatai and the birth pangs of the Yamato kingdom that took its place probably occurred during this period.

It is possible to push the date of unification of the nation back a few decades earlier than 413: a memorial erected in 414 commemorating the achievements of King Kwanggaet’o of Koguryŏ (a Korean state; 2nd century bce–668 ce), describing the fighting between Wo and Koguryŏ on the Korean peninsula from the end of the 4th century into the beginning of the 5th century, makes special mention of a great army sent to the peninsula in 391 by Wo. Such military success presupposes a long period of preparation. The 8th-century Nihon shoki (“Chronicles of Japan”), one of Japan’s two oldest histories, mentions the dispatch of troops by Japan in 369. Such displays of strength would hardly have been possible unless Japan was already significantly unified, and the date of the unification of the country may therefore be about the mid-4th century at the latest.

The Yamato court

Post-World War II historians have greatly revised the view of the place of Yamato in Asian affairs, downplaying the degree of control the Japanese formerly asserted that Yamato held over the Korean peninsula in ancient times. Most divide this period into three stages: a time of growth and expansion from about 250 to the end of the 4th century, a period of florescence that covers the 5th century, and then a period of decline from the early 6th century.