The first five books track the early history of The Silmarillion and related texts. Books six to nine discuss the development of The Lord of the Rings; book nine also discusses the Númenor story in the form of The Notion Club Papers. Books ten and eleven focus on material from the Silmarillion that Tolkien worked on after The Lord of the Rings was published, including the Annals of Beleriand and the Annals of Aman. Book twelve discusses the development of the Appendices to The Lord of the Rings and examines assorted writings from the last years of Tolkien's life.