Arda, also known as Earth, was the world in which all peoples of Middle-earth and of Valinor lived.
History[]
Arda consisted of land masses, chiefly the continents of Middle-earth and Aman, oceans and seas, and an atmosphere. It was a part of Eä, the created World (i.e., of the whole Tolkienian star system). Arda was created, together with the rest of Eä, through the Music of the Ainur, and was set apart as a dwelling place for the Children of Ilúvatar (that is, Elves and Men). When Eä was created, many of the Ainur chose to dwell within it as long as it should last, and they built Arda and chose to reside there. The most powerful of these Ainur were called the Valar, the Powers of the World.
Originally, Arda was flat, rather than spherical (though it still had mountains and valleys), and the Valar built it to a symmetric plan. They lit up Arda with great lamps, and the explosion of biological life that ensued became known as the First Spring. This period ended when Melkor launched a surprise attack, destroying not only the lamps but the layout of the world.
After this time, Arda was surrounded by a mighty ocean, Ekkaia or the Encircling Sea, and the continents were separated from each other by Belegaer, called the Great Sea. During the Years of the Trees, Valinor, the realm of the Valar occupying most of the continent of Aman, was lit up by the Two Trees. Middle-earth was dark. At first it was largely controlled by Melkor and his servants, but when the Elves awoke the Valar went to war against Melkor, defeating him and imprisoning him in the Halls of Mandos for "three ages". During this war, many of the westernmost areas of Middle-earth were drowned beneath the waves.
During the captivity of Melkor, the Valar invited the Elves to dwell with them in Aman. Many Elves accepted this invitation, and set out for the West; these became known as the Eldar. Along the way, some groups of Eldar, notably the Nandor and the Sindar, chose to remain in Middle-earth. The Sindar settled in the region of Beleriand, a north-western coastal area of Middle-earth.
When the Years of the Sun began, Arda experienced the so-called Second Spring, a new period of growth and vitality as a result of the light of the sun in Middle-earth. At that time, Men also awoke in the east of Middle-earth.
At the end of the First Age, Beleriand was destroyed during the War of Wrath, and much of it sank beneath Belegaer; only a few high points, such as Himring (later Himling) and parts of Dorthonion (later Tol Fuin), remained above sea level as islands.
In the Second Age, Númenor was raised in the Great Sea for the Edain. This island existed through most of the Second Age, but was destroyed as a result of the pride of the Númenórean people in defying the Ban of the Valar and sailing to Aman in the west.
During the downfall of Númenor, Arda was made round. The Undying Lands (Aman and Tol Eressëa) were taken out of the world, and could only be reached by the Elves, following the straight road that was granted to them. As Aman was taken away from Arda, new lands and continents were created.
South of Middle-earth was the Dark Land, and east of it was the Land of the Sun.
Arda Marred[]
Arda Marred was the name given to the world as it is: the world after the wars of the Valar and Melkor, and the dispersing of Melkor's Fëa and hröa throughout the world. It is this world from which are formed the Fëa and hröa of the Children of Ilúvatar, and therefore it is at times a cruel and evil world with plagues, extreme colds, heat, and other concepts which do not exist in Arda Unmarred.
Arda Marred also broke the design of Elvish immortality: in Arda Marred Elves slowly fade, until at last they are little more than wraiths. Only in Valinor was this fading delayed, which is one reason all Elves have no choice but to sail to Valinor in the end. One of the special abilities of the Rings of Power was that they could delay the effects of time, and as such were used by Elrond and Galadriel to preserve their realms. After the destruction of the One Ring in the Fourth Age, the Elvish rings' power over time was also lost, so the last of the Eldar had no choice but to leave Middle Earth and sail west for Valinor.
Arda Healed[]
Arda Healed is the prophecy that Arda Marred will be restored: it will be like Arda Unmarred but better, since it will also incorporate all the good things of Arda Marred. Arda Healed will be created after the Dagor Dagorath, when Morgoth will finally be destroyed, and the world broken. Afterwards, a new world will be created and will be known as Arda Healed.
Galadriel's words while parting with Treebeard at Isengard in The Return of the King are "Not in Middle-earth, nor until the lands that lie under the wave are lifted up again. Then in the willow-meads of Tasarinan we may meet in the spring. Farewell!". This might imply that Beleriand will be recovered after the Dagor Dagorath. It is however unknown, since Arda Healed will contain all the good things of Arda Marred, whether Númenor will also be recovered or not.