AMS-dated archaeobotanical assemblages from hearth deposits of Middle Yayoi (fourth century bce–first century ce) cultural layers of the Maenakanishi site (36°09′N, 139°24′E) in northern Saitama Prefecture demonstrate that besides rice, foxtail and broomcorn millet were the most important staple crops during the second and first centuries bce. The reliance on less demanding dry-field crops at Maenakanishi and other Early to Middle Yayoi settlements in north-western Kanto and the Central Highlands in eastern central Japan contrasts with concurrent agricultural production in western and north-eastern (Tohoku) Japan, where rice cultivation generally dominated and millets apparently played a minor role. Two factors, which likely influenced this pattern, are the uneven density distribution and the cultural heterogeneity of indigenous non-agricultural Jomon populations during the formation and spread of the Yayoi culture (tenth/fourth century bce–250 ce) brought to the Japanese islands by farmers from the Asian mainland. In western Japan the spread of rice cultivation was likely promoted by low Jomon population densities. The higher importance of foxtail and broomcorn millet at Maenakanishi may be explained by cultural influence from the northern Central Highlands. Early agricultural communities in this region appear to have preferred these newcomer crops that required less labour and organisational efforts.
