Published after Tolkien’s death, the origins of The Silmarillion reach back sixty years before The Hobbit. The Three Silmarils were jewels created by Feanor, most gifted of the Elves.  Within them was imprisoned the Light of the Two Trees of Valinor before the Trees were destroyed by Morgoth, the first Dark Lord. The jewels were seized by Morgoth for his crown, guarded in the fortress of Angband in Middle-earth.  This is the tale of the rebellion of Feanor and his kindred against the Gods, their exile from Valinor and their return to Middle-earth.