J.R.R. Tolkien’s first published book about Middle-earth’s ancient mythology was The Silmarillion.
The Silmarillion was published posthumously in 1977, edited by Tolkien’s son Christopher Tolkien. It presents the creation of the world, the divine Valar, the Elves, and the great conflicts of the First Age, including the stories of the Silmarils, Beren and Lúthien, and Túrin Turambar.
Tolkien worked on versions of this mythology for much of his life, but he did not complete a definitive final form for publication. Christopher assembled and edited material from manuscripts, making The Silmarillion a carefully constructed posthumous book rather than a novel issued by Tolkien during his lifetime.
The title is sometimes confused with The Book of Lost Tales, an early collection of related drafts, or The History of Middle-earth, Christopher Tolkien’s later twelve-volume study of the evolving texts.