Published in twelve volumes between 1983 and 1996, "The History of Middle-earth" compiles and analyzes a large portion of J.R.R. Tolkien's Middle-earth legendarium. Christopher Tolkien, Tolkien's son, edited and assembled the books. In order to shed light on the creative process behind Tolkien's epic works, such as The Lord of the Rings and The Silmarillion, the series gathers and examines various versions of the lore and stories contained within his legendarium.
Having been working on his Middle-earth stories since the 1910s, Tolkien left behind a vast amount of unfinished work by the time of his death in 1973. After arranging and revising this material for the next twenty years, Christopher Tolkien published "The History of Middle-earth".