The Druid Histories, kept in Paranor, are magical tomes written and maintained by the Druids. They chronicle the known history of the Old World and New World, with particular focus on magical, supernatural, and mystical phenomena.
The Great Wars destroyed most of the knowledge of science and the little that remained was so corrupted that it was unable to be put to use. When Galaphile founded the Druid Order, his goal was to pool together the remaining knowledge of all the Races and to use it for the betterment of all peoples. The creation of the Druid Histories are one of the direct results of those efforts.
The tomes are held in the library in Paranor in a special crypt created by Allanon. Before that, Bremen gave the Druids' librarian a bag of magic powder with which to render the Histories invisible to prevent them from being seized by Skull Bearers.
The Druid Histories also contain the history of the Druid Order. Many Druids are historians, and one of the jobs of the Druid Order is to continuously update these histories.
The Druid Council had various positions, including warrior Druids like Risca, and mystics like Bremen. Allanon and Walker Boh are the most famous of the Druid historians, probably in part due to their many years of service as the sole remaining Druid in all the Four Lands. While the keeping of records was important to the Druid Order during the times a functioning Order actually existed, there were many different areas for Druids to focus on.
The Druid Histories have a safeguard to protect them against danger: When threatened, they explode with magical fire and return themselves back to the vault in Paranor where they are normally stored. Anyone in possession of them when this happens will also be transported, as illustrated by Cogline and Rumor's escape when they were attacked by Rimmer Dall and the Shadowen at Hearthstone.