In the old testament times, God had instructed the people to always tell each the events that took place in history - basically what God was showing them and doing for them (children of Israeal. He told them to tell their children, and their children were to tell their children, etc. To carry on the history of what took place and to not forget what God had done for them.
[Joe 1:3 KJV] 3 Tell ye your children of it, and [let] your children [tell] their children, and their children another generation.
Some probably even wrote them down to preserve them.