Gu, which were ritual vessels used for wine, are one of the most recognizable of bronze forms of the Shang dynasty. The vessels date to as early as the Erlitou period, circa 2000 to 1500 BC, at which time they were a simple slender beaker, and eventually evolved into the elegant trumpet-mouthed vessel of the late Anyang period of the 12th - 11th century BC date. This ritual wine beaker is associated with the 'mature' type of gu from Anyang (late 13th to early 12th Century BC), which exhibit the same distinctive structure with the same decorative sequence of motifs. A similar is example is included Ritual and Reverance, The University of Chicago, 1989, p. 46, no. 15; another related group from the Arthur M. Sackler Collection, is illustrated by Robert W. Bagley, Shang Ritual Bronzes, pp. 239-247, nos. 32-35.