The Sith Archives was a hidden storehouse of Sith knowledge created after the establishment of Darth Bane's Order of the Sith Lords. Within the respository resided stories and legends of the most glorious Sith Lords.
Darth Sidious was known to had access to the Archives and showed it to Darth Maul. The Sith apprentice went through it for long hours before he came upon an overlooked entry of a Sith Lord thousands of years ago who wielded a double-bladed lightsaber, which the Zabrak would adopt as his weapon.
During his training, Darth Maul began a journal in the hope that his writings would be included within the contents of the Sith Archives.