The features of the masks of each of these plaques is similar to those seen on other jades of Neolithic or early Shang date (2500-1500 BC), such as those illustrated as line drawings by J. Rawson, Chinese Jade from the Neolithic to the Qing, British Museum, 1995, p. 200, fig. 1. See, also, the more complete altered jade mask similar to the second piece in this lot excavated in 1989 from a Shang tomb in Dayangzhouxiang, Xin'gan county, Jiangxi province, illustrated in National Treasures - Gems of China's Cultural Relics, Hong Kong Museum of Art, 1997, pp. 140-1, no. 51.