Sue ware represents a decisive turning point in the history of Japanese ceramics, marking a break with the long tradition of producing earthenware. Largely as a result of innovations introduced by immigrant Korean potters, sueki (sue ware) was technically more advanced than wares of the preceding Jomon and Yayoi cultures. Japanese craftsmen began to use the potter's wheel during this time, as revealed by the even, relatively thin walls of this bottle's neck. Fired at a higher temperature than previously achieved—roughly 1000 to 1200° C, in the range of modern stoneware—Sue wares have hard, bluish gray bodies. They were fired in Korean-style kilns, known as anagama in Japanese, which were single tunnel-like chambers half buried in the ground along the slope of a hill.The mottled greenish brown glaze that coats most of this vessel's surface represents an early stage of another important development in pottery production. In this case, the glaze was formed when ash from the burning wood accidentally settled on the bottle during firing and fused to its surface in the hot temperature of the kiln. As this effect became desirable and potters learned to control the process, ash glaze was applied intentionally.