The uniquely shaped ch'a-tou with its exceptionally wide mouth is a type of waste receptacle that may have also functioned as a spittoon. Its shape evolved from T'ang dynasty (610-906) silver vessels and examples have survived in a variety of glazes including yueh celadon, white, black, and ching-pai (shadow blue). The form appears to have been most popular during T'ang (618-906) and Northern Sung (960-1127). This is the period when tea drinking became popular in China suggesting that this unusual type of vessel may have served as a waste receptacle for tea dregs.