There is a description in "Sengaikyo" (oldest topography of China), written sometime between the Warring States Period and Qin/Han Dynasty) that says Wa was obedient to Yan (Chunqiu period) which was in the northeast of China, therefore it is considered to be in the period from the sixth century to fourth century B.C. but some think the book should also be taken with caution.
『山海経』（戦国-秦漢期成立）には倭が中国東北部にあった燕_(春秋)国に服属していたという記述があり、紀元前6-4世紀頃のことと考えられているが、同書についても依拠することに慎重な見解が存在する。