Metal mines produced in Japan are limited, so metal utensils are often related to high status. However, holding metal "symbols" was not the only factor that made the society more and more hierarchical at that time. Like most agricultural development, rice cultivation reduces the resource base within society, making it easier for social elites to control social resources. Rice cultivation also leads to more permanent settlement, wider land confirmation and the need to defend and expand borders, especially when the population increases to about 2 million. With the increase of fighting, people with metal weapons and the ability to summon soldiers will further improve their social status. Of course, there are more and more battles between tribes, which makes tribes rank according to the outcome of the battle.
In this increasingly hierarchical world, slavery is common. When people with low status meet people with high status on the road, they retreat to the side of the road and bow to let the latter pass-this custom continued until the19th century. Classes are distinguished by titles. Men with high status have four or five wives, while men with low status also have two or three wives.
Another factor that accelerates stratification is wealth, especially the wealth brought by business. Some tribes are lucky. They have metal resources in their territory. Some tribes have benefited from the development of new technologies, such as silk produced in Kyushu from about 1 century. Glass technology and metallurgy have also developed. Product diversification has led to an increase in transactions, including transactions with the mainland and transactions on the island, and there is a market in every region. Asahi, Aichi Prefecture is such a trading center, which is the largest Yayoi settlement site discovered so far, with an area of about 0.8 square kilometers, while the typical settlement is between 0.02 and 0.28 square kilometers.
Tribal strife, the emergence of elites and the struggle for control resources have led to an increase in politicization. Many tribal leaders have formed alliances with neighboring tribes and formed countless small kingdoms. Tombs include urn-coffin tombs, sarcophagus tombs, sarcophagus tombs, earth-covered tombs and square tombs with ditches around them. The distribution of urn coffin tombs and stone tombs is limited to the northern part of Kyushu. In addition to northern Kyushu, sarcophagus tombs were also found in Yamaguchi Prefecture in western Honshu. Square Zhougou tombs of Tukou tombs are distributed in Kyushu and Honshu, covering a wide range, and some tombs use wooden coffins. Most of the bodies in various tombs are straight limbs. Most tombs have little or no funerary objects, but a few tombs in northern Kyushu, such as Tamaki Temple Tower in Saga Prefecture, Sanyun, Sujiu and Pingyuan in Fukuoka Prefecture, have a large number of precious funerary objects, including bronze swords, spears, mirrors, various beads and glass walls. This shows that there were a few dominant people in society at that time, and they had a lot of wealth.