Yongle tianbai or 'sweet white' glazed ewers of this form are Tibetan in origin and are either undecorated or incised with foliate scroll or the bajixiang, as in the present example.
Similar ewers, with and without incised decoration have been excavated at the Ming imperial kiln sites. Cf. a ewer included in the exhibition, Imperial Porcelain of the Yongle and Xuande Periods, excavated from the site of the Ming Imperial factory at Jingdezhen, Hong Kong Museum of Art, 1989, illustrated in the Catalogue, no. 8; where it has been mentioned that white-glazed monk's cap ewers should be dated to the early Yongle period, ibid., p. 98. For a discussion by Liu Xinyuan on tianbai wares, ibid., pp. 71-73.