at
Kushiro,
Hokkaido , Hokkaido Iron tools seem to have prevailed around the end of
Zoku-Jōmon period, so that stone tools disappeared in the Satsumon period. Among subsistence activities, hunting, gathering, and fishing remained the most important. Locations of large settlements at estuaries indicate the importance of
salmon. Although cultivation of
buckwheat and
barley is presumed for the Zoku-Jōmon, reliable evidence shows that the Satsumon additionally cultivated
rice,
wheat,
sorghum, various types of
millet,
mung bean,
perilla,
melon,
adzuki bean and
hemp. Many of these plants were likely imported from mainland Asia. Opinions divide among those who, taking Satsumon culture as the periphery of the Kofun culture of the mainland, argue that such crops supplied a large portion of the diet, and those who think it provided only a small part and the culture was basically a continuation of the Epi-Jomon. A study of pottery residue on
Rebun Island sheds light on how the Satsumon culture adapted to a new environment. Unlike their mainland counterparts, who combined farming with hunting and gathering, the Satsumon people on Rebun Island appear to have relied more heavily on marine resources, such as fish and shellfish. This shift in subsistence strategy suggests that the island's ecosystem was not ideal for their established mixed farming and hunting practices. The focus on marine resources may also explain why the Satsumon presence on Rebun seems to have been relatively short-lived. == Society ==