In general the Wajin that established themself on the Japanese archipelago became the Yayoi people, the ancestors of the Yamato people. The word "Wajin" also refers to related groups outside of Japan. The first secure appearance of Wajin is in "Treatise on Geography" of the Book of Han. After that, in "Gishi WajinDen", a Japanese abbreviation for the "account of Wajin" in the "Biographies of the Wuhuan, Xianbei, and Dongyi", Volume 30 of the "Book of Wei" of the Records of the Three Kingdoms ), their lifestyle, habits and the way of society are described and by cultural commonality such as lifestyle, customs and languages, they are distinguished themselves from "Kanjin" and "Waijin". Descriptions about Wajin can be found in the Old Book of Tang and the New Book of Tang Several linguists, including Alexander Vovin and Juha Janhunen, suggest that Japonic languages were spoken by Wajin and were present in large parts of the southern Korean Peninsula. According to Vovin, these "Peninsular Japonic languages" were replaced by Koreanic-speakers. This event was possibly the reason for the Yayoi-migration into Japan. Janhunen also suggests that early Baekje was still predominantly Japonic-speaking before they got replaced or assimilated into the new Korean society.
The ethnic concept of "Wa-zoku " encompasses a wide range of regions and does not limit to the Wajin of the Japanese archipelago. According to Kenzaburo's theory, Wa-zoku are Wajin who came to the Japanese archipelago with rice crop, whose ancestor was the same as the Yayoi people. Torigoe says that the original place of the Wa-zoku is Yunnan. Suwa Haruo considered Wa-zoku to be part of Baiyue in southern China. The Wajin are possibly descendants of the Wu people. A large paddyruins in the area was created around 450 BC, the Warring States period, in Kyushu, and a record states that "Wajin self-named descendants of Zhou". An influential theory states that the Wu people of the Yangtze River area that followed the hydroponicrice cultivation culture, which is also a symbol of Yangtze civilization, drifted to the Japanese archipelago around the 5th century BC, in collaboration with the destruction of the Kingdom of Wu.
