Sue ware traces its roots to the high-fired stoneware of the Korean peninsula, and the Korean influence is strong in early Sue ware forms. The appearance of Sue ware marks the first major technological advance in the history of Japanese ceramics. Innovations included the use of the wheel to produce large numbers of pots, and the introduction of the anagama (hill-side kiln) which made it possible to fire at high temperatures in reduction. The new pottery techniques which were transmitted to Japan from the Korean peninsula originated in the gray ware of Shang dynasty China. A well known area where Sue ware was produced is the group of ancient kiln sites in Suemura in the hilly area of southern Osaka. Pottery activity is thought to have begun there in the Kofun period in the early 5th century, after which the new technology spread to the rest of the country. Vessel forms changed greatly in the 7th century, when potters began to make vessels modeled on metal ware from China and Korea. Sue ware began to decline in the late Nara period with the development of pottery glazed with ash and other glazes; the technology of Sue ware, however, formed the foundation of the medieval pottery which was to come. Along with medieval wood-fired ware with natural glaze, this ware can be classified as one kind of stoneware.