History of Middle-earth is a monumental 12-volume series edited by Christopher Tolkien
Do you need help searching for specific themes (like the origin of Orcs or Elves) within the 12 volumes?
Ultimately, The History of Middle-earth is not just a collection of stories; it is the biography of a world. It reveals J.R.R. Tolkien as a perfectionist who constantly revised his work, proving that Middle-earth was not a static setting, but a living, breathing project that occupied a lifetime.
Availability: Some volumes go in and out of print, making digital copies a reliable alternative. Legal and Ethical Reading
Volume 5: The Lost Road and Other Writings
Focuses on the linguistic obsession of Tolkien. Introduces the "Downfall of Númenor" and the concept of time-travel via "The Lost Road." Also includes the "Lhammas" (account of Elvish language relations).
Vol 3: The Lays of Beleriand: Beautiful, long-form poems about Beren and Lúthien and Turin Turambar.