This vessel is particularly unusual for its minimalist appearance, lacking surface decoration except for three raised ribs. Zun of this type are discussed by Jessica Rawson in Western Zhou Ritual Bronzes from the Arthur M. Sackler Collections, Washington D.C., 1990, p. 67, where she notes that plain vessels were recovered in the area of the Xing fief in Yuanshi county, Hebei province, and are datable to the latter part of the early Western Zhou period. Richly decorated vessels were also excavated at this site, suggesting that the two styles coexisted.
Two zun of this type in the Arthur M. Sackler Gallery, Smithsonian Institution, Washington D.C., are illustrated ibid., vol. IIB, pls 85 and 86, the first decorated with two ram’s heads and illustrated with two further examples, figs 85.1 and 85.2, the second left plain; and two undecorated zun are illustrated in Jung Keng, ‘The Bronzes of Shang and Zhou’, Yenching Journal of Chinese Studies, Monograph Series no. 17, 1941, pls 523 and 543, together with one with a handle, pl. 532.