We build on the model of Chapter 3 to explain how sedentism could have developed in response to better climate conditions involving higher means and lower variances for temperature and rainfall. Sedentism is defined to mean a willingness of human populations to stay at the same site for multiple generations despite occasional periods of low productivity in relation to other sites. We identify three causal channels leading to sedentism. First, there is a short-run channel where climate improvement leads agents to remain at sites when weather there is temporarily bad, because when conditions are harsh, they are less harsh than they were under the previous climate regime. Second, there is a long-run channel where better climate leads to higher regional population. This causes some people to remain at sites where weather is temporarily bad because sites with good weather are now more heavily occupied than before. Finally, there is a very-long-run channel where higher regional population leads to the use of previously latent resources and technological innovation. These mechanisms help to explain the rise of large sedentary communities in southwest Asia during the Epi-Paleolithic and in Japan during the early Holocene.

This chapter examines the origins and early history of violence in the Japanese Islands, focusing on the Jomon (c. 14,500–900 BCE) and Yayoi (c. 900 BCE– 250 CE) periods. For several reasons the Japanese archipelago is a good place to think about links between violence and historical change. It possesses a long sequence of hunter-gatherer settlement that can contribute to ongoing debates over violence and agriculture. Hunter-gatherers in the Japanese Islands display great diversity due to both ecological and historical factors. The fact that many in prehistoric Japan were engaged in plant cultivation, leads us to a third factor: if agriculture was an important stimulus behind organised warfare, then at what point along the continuum between forager cultivation and full-scale farming did violence take on that new mantle? Finally, the position of Japan at the periphery of the East Asian world system offers the opportunity to investigate the role of ‘tribal zone’ and similar colonial processes in contexts very different from those theorised in the existing literature.