Middle-earth is a fictional place which is the setting for most of the stories of author J. R. R. Tolkien. These stories include The Hobbit and The Lord of the Rings. Tolkien's stories chronicle the struggle to control the world (called Arda) and the continent of Middle-earth, between the angelic Valar, the Elves and their allies among Men; and the demonic Melkor or Morgoth (a Vala fallen into evil) and his minions, mostly Orcs, Dragons and enslaved men. In later ages, after Morgoth's defeat and expulsion from Arda, his role is continued by his acolyte Sauron. The Valar withdrew from direct involvement in the affairs of Middle-earth after the defeat of Morgoth, but in later years they sent the wizards or Istari to help in the struggle against Sauron. The most important of these were Gandalf the Grey and Saruman the White. Gandalf remained true to his mission and proved crucial in the fight for Sauron's destruction. Saruman however, became corrupted, and sought to establish himself as a rival to Sauron for absolute power in Middle-earth. Other races involved in the struggle against evil are Dwarves, Ents and most famously Hobbits. The early stages of the conflict are chronicled in Tolkien's work The Silmarillion, while the final stages of the struggle to defeat Sauron are dealt with in his works The Hobbit and the main text of The Lord of the Rings.
A recurring theme in the stories is that the focus of conflict is on the possession and control of precious or magical objects. The First Age of Middle-earth is dominated by the doomed quest of the Elf Fëanor and most of his Noldor clan to recover the three precious jewels called the Silmarils (hence the name Silmarillion), stolen from them by Morgoth. The Second and Third Age are both dominated by the forging of the Rings of Power, and in particular by the fate of the One Ring forged by Sauron, which grants its wearer the power to control or influence all those wearing the other Rings of Power (hence the name The Lord of the Rings).
Tolkien prepared several maps of Middle-earth and the regions of Middle-earth in which his stories took place. Some were published in his lifetime, though some of the earliest maps were not published until after his death. The main maps were those published in The Hobbit, The Lord of the Rings and The Silmarillion. Most of the events of the First Age took place in the subcontinent Beleriand, which was later subsumed by the ocean at the end of the First Age; the Blue Mountains at the right edge of the map of Beleriand, are the same Blue Mountains that appear on the extreme left of the map of Middle-earth described in the Second and Third Ages. Tolkien's map of Middle-earth however only shows a small part of the world; most of the vast lands of Rhûn and Harad are not shown on the map, and there are also other continents altogether.
Tolkien said that his Middle-earth is located on our Earth, but in a fictional period in the past, estimating the end of the Third Age to about 6,000 years before his own time. He was later to reject this notion, and state that Middle-earth was not at a physically distant time, but rather "at a different stage of imagination".