The yi was a water vessel that was often used in conjunction with a pan for the ritual washing of hands, which is confirmed by the two having been found together in tombs, usually with the yi in the pan. It was a late Western Zhou adaptation of the gong and the he, and continued into the Eastern Zhou period.
Although the shape of the present yi is similar to others of Spring and Autumn date, the decoration appears to be unique. The combination of bands of interlaced dragon pattern and grooves is similar to that seen on a fanggui, dated 7th century BC, formerly in the Tsui Museum of Art, illustrated by J. So, Eastern Zhou Ritual Bronzes from the Arthur M. Sackler Collections, p. 30, figs. 29a-d, and subsequently sold in these rooms from the Jingguantang Collection, 18 September 1997, lot 117. Small feline-like animals decorating the Tsui vessel are also similar to those found on the handle of the present yi. So refers to the type of angular dragon scroll in the bands on the Tsui fang gui as being typical of bronzes from Qin territory. Similar scroll also decorates the sides of a ding in the Art Institute of Chicago, illustrated op.cit, p. 105, fig. 6.7, where it is identified as probably from Qin, and dated to the 2nd quarter of the 7th century BC.