Early, Middle, and Late Yayoi Period(Approx. 2,300 - 1,700 years ago)
In this period people who had been living inland on the Ryukyuan limestone hills migrated to the seashore. Excavation of the shell mounds revealed the presence of a large number of giant clam shells used as sinkers leading researchers to believe the people used nets to harvest fish.
The replacement of stone tools for iron and copper utensils from excavations indicate that there was active trading overseas during this period. The Tricornis latissimus and Conidae shells harvested in Amami and Okinawa were transported to Kyushu where they were processed into shell products such as the Kaiwa shell bracelets which were traded throughout the whole of Japan. The products traded for are believed to be Yayoi pottery vessels. The Yayoi period ruins in the prefecture yielded the same type of pottery excavated from Kyushu Yayoi period sites.