Surface decorations on gu can include tao tie motifs, geometric designs and cicada images among other common designs. Bronzes are some of the most important pieces of Chinese art, and warranted an entire separate catalogue in the Imperial art collections. The Chinese bronze age began in the Xià dynasty, and bronze ritual containers form the bulk of the collection of Chinese antiques, reaching its zenith during the Zhōu dynasty. The appreciation, creation and collection of Chinese bronzes as pieces of art and not as ritual items began in the Sòng dynasty and reached its zenith in the Qīng dynasty in the reign of the Qiánlóng emperor, whose massive collection is recorded in the catalogues known as the Xīqīng gǔjiàn.