Mirrors, which were brought to Japan from the Korean Peninsula and China during the Yayoi period (ca. 400 B.C.-ca. A.D. 250), served as important ceremonial implements for rituals from the Yayoi through the Kofun (ca. 250-ca. 600) periods. The faces of the mirrors were generally convex and polished with mercury, while the backs were decorated with various designs with a knob attached in the center to pass a string through. Mirrors are usually exhibited to show the decorations on the back, but these works are displayed face up.