The material on which the oldest Chinese books were recorded?

They were bamboo plates. These bamboo plates were collected and dried. Then they were tied together and formed a book. For example, the ancient Hindus wrote on bamboo, and on palm leaves, which were also cut, dried, and then tied together, thus creating a book of palm leaves. The Egyptians were more advanced in this regard. They were able to create papyrus from reeds, on which they wrote with ink.