The Controllers eradicated history as it was seen to be dangerous for people and they had no need to know it. In the society of Brave New World, people are taught only things which are relevant to their place in society. Therefore there would be no need for history, the people lived entirely in the moment and were encouraged to do so. Even forming relationships with people was looked down upon as you would then build up a type of history with that person and reflecting on this would cause you unnecessary introspection and upset the balance. Therefore all previously known history is kept locked up by the Controllers.