A proto-historical period in Japanese history, broadly 300 bc toad 300. The agricultural economy was based on wet-rice cultivation. Sites of the period include mound burials for Yayoi rulers, family burial grounds for others, and moated settlements. Genetically, Yayoi people are thought to be descended from the Jomon, and this link is visible in the succession of pottery styles, although links with other areas are also evident. Bronze and iron were used. Warfare and the degree of social differentiation present increased during the period.