People were waiting a long time for it, since Tolkien told people after LotR came out it was his next project, and answered lots of fan mail from people asking about it, what happened and so on. He also spent an immense amount of time rewriting THE SILMARILLION to include LotR and HOBBIT characters that did not exist when he first started writing THE SILMARILLION in 1917, such as Galadriel, Celeborn, Elrond and others.

It can be classified as a prequel, and thus as not part of the same narrative drive that began with THE HOBBIT. However, it also provides a different context in which THE LORD OF THE RINGS can be read. In Humphrey Carpenter's biography, Tolkien even considers THE LORD OF THE RINGS to be a sequel (though more correctly a thematic one rather a plot one) to THE SILMARILLION. Notably, in THE SILMARILLION itself Tolkien adds the events of LORD OF THE RINGS to the end and links the War of the Ring and the defeat of Sauron to the defeat of Morgoth and the 'thinning' and eventual departure of the elves from Middle-earth.