Why do we not know if any dynasties preceded the shang?

There is limited archaeological and historical evidence available for earlier dynasties in ancient China, making it difficult to definitively determine if any dynasties preceded the Shang dynasty. The Shang dynasty, which existed from approximately 1600 to 1046 BC, is the first Chinese dynasty for which there is significant written record and archaeological evidence. Prior to the Shang dynasty, there are myths and legends about earlier rulers and dynasties, but these are not well-documented or confirmed by historical evidence. As a result, it is uncertain if any dynasties existed before the Shang dynasty, and further research and discoveries may be needed to uncover more information about ancient Chinese history.