古墳時代
are curved, comma-shaped beads that appeared in prehistoric Japan from the Final Jōmon period through the Kofun period, approximately 1000 BCE to the 6th century CE. The beads, also described as "jewels", were made of primitive stone and earthen materials in the early period, but by the end of the Kofun period were made almost exclusively of jade. originally served as decorative jewelry, but by the end of the Kofun period functioned as ceremonial and religious objects. Archaeological evidence suggests that were produced in specific areas of Japan and were widely dispersed throughout the Japanese archipelago via trade routes.