The History of Middle-earth is a 12-volume series that chronicles the development of J.R.R. Tolkien's fictional world, Middle-earth, and the legendarium surrounding it. The series was edited by Christopher Tolkien, J.R.R.'s son, and published posthumously.

The History of Middle-earth series offers a fascinating insight into J.R.R. Tolkien's creative process and the evolution of his fictional world. The 12 volumes provide a comprehensive understanding of the mythology, languages, and histories of Middle-earth, making it a valuable resource for scholars, researchers, and fans of Tolkien's work.