The green-glazed stoneware of the Yaozhou kilns in Shaanxi province are considered among the finest ceramics of the Northern Song period. The best pieces were often requisitioned by the court. Potters employed a wide range of techniques, including carving, incising, moulding, appliquéing and modelling. Bowls like this one were used for tea drinking, appreciated by the upper classes and the emperor himself. Associated with Buddhist beliefs, tea acquired an almost mystical value. It was never brewed in a teapot; rather, the dried leaves were ground to a fine powder and then put in a tea cup and infused with boiling water.