Many round imported mirrors and their domestic copies are found from Yayoi and Kofun graves. They are flat and shiny on one side, with a raised rim and decorative designs and inscriptions arranged around one or more knobs with holes on the other. Most are of Chinese derivation, but several mirrors with geometric designs, which are traced through Korea to northern Eurasia, have been found from Yayoi graves. Domestic production began in the Late Yayoi period (3rd century) and continued throught the Kofun period. The Nara period (8th century) saw the development of domestic styles, initially inspired by Tang mirrors. A number of distinctive styles, later with handles, were made in the Heian, Kamakura, Muromachi and Edo periods. Misisil Cave. A limestone cave in southwestern New Britain, which has yielded obsidian tools from the Talasea source, dated to about 9000 be. The site represents the earliest known evidence for human settlement in the islands east of New Guinea and also the earliest date for the use of obsidian in this region. See also Balof Cave.