Black glazed ewer with straight shoulder line design, Jizhou ware, Song Dynasty (960-1279) [Photo provided to chinadaily.com.cn]

The black glazed ceramics of Jizhou Kiln were closely tied to the tea-drinking culture during the Song Dynasty (960-1279). Dou cha, or 'tea-battles', were very popular at that time – people would put ground tea powder in their cups before pouring in boiled water to form a white foam, and the person who had the longest-lasting foam in the cup was deemed the winner. The black glazed cups were best suited for this game as they made observing the foam easier.