Tolkien's legendarium is the term for the entirety of
J. R. R. Tolkien's
mythopoetic writing that forms the background to his
The Lord of the Rings. Tolkien worked and re-worked the components of his legendarium throughout his adult life, or during a period of more than 50 years; the earliest drafts, published in
The Book of Lost Tales (1983) dating to 1916.