One of the most important technical innovations of the Tz'u-chou kilns was overglaze painted polychrome decor. Enamel overglaze painting, one of the most celebrated traditions of Ming (1368-1644) and Ch'ing (1664-1911) porcelain production, can be traced to Tz'u-chou kilns of the late Sung and Ch'in (1115-1234) periods. Designs in red, yellow, and green enamel are painted in glazed and pre-fired plain white pieces. They are then fired at a lower temperature. The majority of these early polychrome vessels were small, shallow bowls and dishes like this example.