Celadon glaze is the earliest color glaze of Chinese porcelain. It is not purely blue, mostly with yellow, grey or green. Celadon glaze was first seen in Shang Dynasty, and had been fired in successive dynasties. During the Ming and Qing Dynasties, although the painted porcelain was the mainstream, the traditional celadon glaze was still unique. The celadon glaze made in Boshan kiln in the Ming Dynasty has a rather uniform and clean color. Zibo Zhaili kiln is the only celadon kiln site of Northern and Southern Dynasties discovered so far in Northern China. This is a representative celadon bowl of Northern Qi Dynasty.