Twenty-two bronze nao-bells dating to the late Shang and early Western Zhou periods have been unearthed from the five southern provinces of Hunan, Jiangsi, Zhejiang, Jiangsu, and Fujian. Of these, sixteen were from Hunan, three from Zhejiang, and one each from the remaining three provinces. These bells can be classified into four categories: type A has an animal mask decoration (eleven examples); type B has a cloud pattern (three examples); type C has nipples (only one example); type D has stalks (mei, seven examples).

The nao is a bell that can produce two tones. It can be used in sacrificial offerings as well as war. Because most of these bells have been discovered at the top, mid-section, or foot of mountains or on the banks of a river, we surmise that they may have been used in contemporary sacrifices to the mountains and streams, wind and rain, and stars, etc. Based on the periodization of the style of their shape and decoration we conclude that type A may be as early as late Shang, type B can be assigned to the end of the Shang, type C is from the beginning of the Zhou and type D belongs to the early Western Zhou. They developed from type A to B to C to D and then to the yong-bell. The characteristics of southern nao bells are: they are large, thick and heavy; most have whorls on the circular handle; many animal masks and cloud and lightning patterns are formed from thick lines among the decoration; the entire body is usually covered with decoration; most appear singly, and they were set up on their stands with the mouth facing up. In contrast, northern nao-bells are very small, they have no whorls on the handle, their decoration is simple, and they are unearthed in groups of several together.