What is the purpose of painting gravel in Azhili Cave? What is the explanation?

However, the use of these gravels remains a mystery. At present, there are at least three different explanations. Some people think that this is a tool of witchcraft or divination. Some people think that it is a symbol of primitive notes and has the embryonic form of words; Others put forward a hypothesis that this is the earliest currency of mankind, which is used to replace an intermediate in barter.