Description of Ages

First Age: The Elder Days
The beginning of the recorded ages of Arda. Though it is not established when it started, I would suppose that it began with the completion of Eä even though FA 1 coincides with the first Year of the Sun.

The first part of the age includes the Spring of Arda, when the Valar created the Two Lamps and lived in Almaren; the Sleep of Yavanna (Aulë created the dwarves, the awakening of the Elves in Cuivíenen, the start of their journey to Aman and Melkor's capture and imprisonment in the halls of Mandos); and the succeeding Noontide of Valinor, which lasted for three ages. The end of that era came during the Darkening of Valinor when Melkor and Ungoliant poisoned the two trees, killed Finwë and stole the Silmarils. As a reaction, the Noldor rebelled, resulting in the Kinslaying at Alqualondë and the Doom of the Noldor. Also by this time, the Moon and the Sun first rises (hence the Years of the Sun began) and Men had woke in Hildoríen.

As the Noldor entered Beleriand, the Wars of Beleriand started (which is one of the subjects of The Silmarillion) and lasted for almost six centuries. It was marked by six major battles. The first was a battle between the Orcs of Morgoth and the Elves of Region (led by Thingol) and Ossiriand (led by Denethor). The second battle was Dagor-nuin-Giliath by a third army of Morgoth against the Noldor of Fëanor at Losgar. Dagor Aglareb was the third, a sudden attack on Dorthonion by Morgoth which was repelled and destroyed by the Elves, led by Fingolfin and Maedhros. During this time the Siege of Angband began, which brought about the Long Peace (FA 260-455). Morgoth suddenly broke the siege by sending out flames which burned out all of Ard-galen. This was the start of the fourth battle, Dagor Bragollach in the winter of FA 455. Although the Ered Wethrin, the Pass of Sirion, Aglon and Himring was defended, Maglor's Gap, Thargelion and the whole of Dorthonion was lost to the Noldorin forces. In FA 473, the Union of Maedhros was formed but the greater strength of Morgoth and the treachery of the Easterlings led the Noldor into the fifth battle, Nirnaeth Arnoediad. Many of the leaders and warriors of the Eldar and the Edain were killed and Hithlum, Himring, and even the Falas were captured or overran by Orcs. Later, most of the secret elven realms and kingdoms were sacked one by one, from Nargothrond, to Doriath and lastly, Gondolin. West Beleriand was taken earlier and the rest of Beleriand was now open to Morgoth. Thinking that he had already won complete, he relaxed his guards. Eärendil managed to arrive at Valinor and obtain the help from the Valar and the other Elves. Soon the last battle of the wars began, the Great Battle, where the Host of Valinor destroyed Morgoth, broke Angband and cast him out of Eä. But Beleriand was so destroyed that it sank into the Sea.

Second Age: The Black Years
The Second Age began with the end of the Great Battle, the casting of Morgoth out of Eä and the destruction of Beleriand. In SA 32, the Edain was rewarded for their loyalty and valor during the Wars of Beleriand by the Valar by giving them Numenor and they became wisest and most powerful among all Men. Later, the Numenorian returned to ME to help the other races of Men free themselves from the Shadow.

For their part, the Eldar had had founded elven realms thoughout the land, from the realm of the last High King of the Noldor, Gil-galad in Lindon; Celebrimbor in Eriador; Galadriel and Celeborn in Lorien; Thranduil in Greenwood the Great; and later in SA 1697, Elrond in Imladris. Meanwhile, the Dwarves had discovered mithril in Khazad-dum and later had forged a friendship with the Gwaith-i-Mírdan due to their common interest in the art of crafts. Sauron, on the other hand, had gathered power great enough to establish his stronghold, Barad-dur, in Mordor. He approached the Noldor of Eregion and they created the Rings of Power. After Sauron's treachery in forging the One Ring, he killed Celebrimbor and initiated the War of the Elves and Sauron (1693-1701), where Eriador was overran by Sauron's troops. The war ended when Numenor sent a navy and with their aid, Sauron was defeated.

During this time, the Numenorians grew proud and discontented of their mortality. As a reaction to Sauron's claim to be the "King of Men", Ar-Pharazon humbled Sauron in 3262 and took him to Numenor. Sauron quickly corrupted Numenor. It resulted in civil anarchy, the renouncement of the Valar and their worship of Morgoth. Advised by Sauron, Ar-Pharazon had decided to go to Aman and take the right to immortality by force. On the time that his force landed on Aman in SA 3319, the Valar called upon Iluvatar and He changed the world, removing Aman from Arda, destroying Numenor, creating new continents and oceans, and making Arda into a globe. Elendil, his family and some of the Faithful had escaped and returned to ME, where they founded the kingdoms of Arnor and Gondor in 3320.

After the Fall of Numenor, Sauron returned to Mordor and marshaled his forces to attack Gondor in 3429. In SA 3430, Elendil and Gil-galad formed the Last Alliance of Elves and Men, and in the Battle of Dagorlad, crushed Sauron's forces and besieged Barad-dur. The Second Age ended in 3441, when Sauron was overthrown at the slopes of Orodruin, though both Elendil and Gil-galad were slain.

Third Age: The Fading Years
The Third Age began with the defeat of Sauron by the Last Alliance and the death of Elendil and Gil-galad. But the One Ring was not disposed and was taken by Isildur as his own. His action had led to his death and the disappearance of the One Ring at the Disaster of Gladden Fields in TA 2.

During the Third Age, most other races kept mostly to themselves. At about TA 1000, the order of Istari entered ME to unite and counsel the Free People against Sauron. As for the Elves, although they had participated in the war against Angmar and very much later in the War of the Rings, they did little interaction outside of their realms. The Dwarves on the other hand were beleaguered by problems of their own doing. In TA 1980, while extending their mithril mines, they had accidentally released a balrog hidden in the depths of Khazad-dum. The Dwarves fled and Sauron filled Khazad-dum with Orcs. The killing of Thror in TA 2790 led about the War of Dwarves and Orcs (TA 2793-2799) and though it ended with the Battle of Azanulbizar in 2799, Khazad-dum was lost to them because of the balrog.

The Kingdom of Arnor did not prosper and at TA 861, it was split into three kingdoms, Arthedain, Cardolan and Rhudaur. The beginning of the fall of the Northern Kingdoms came when the Kingdom of the Witchking, Angmar rose at about TA 1300 and attempted to destroy the Dunadan of the North. Although the three kingdoms were destroyed, the Witchking's forces were defeated in the Battle of Fornost at TA 1975 and his army driven out of the North.

The Kingdom of Gondor was also beset by problems, the largest of all are the Kinstrife (TA 1432-1448), the great civil war which resulted in the loss of the Palantir of Osgiliath and the creation of the Corsairs; the Great Plague (TA 1636-1637), which had swept across Middle-Earth, reaching even up to Eriador; and the invasion of the Wainriders (TA 1851-1954) which had not only sapped Gondor's strength and population but had killed many of the Line of Anarion. In TA 2050, with the death of Eärnur, the Line of Anarion failed and Gondor was ruled by the Ruling Stewards until the restoration of the kingdom by Elassar Telcontar in TA 3019.

Later developments in the TA included the founding of the Kingdom of Rohan by the Eotheod in TA 2510 and the rise of the Rohirrim; and the Quest of Erebor by Thorin in TA 2941, ending with the Battle of the Five Armies and unexpectedly resulted in the finding of the One Ring by Bilbo Baggins.

Sauron in the TA was cautious but not idle. He rose again at about TA 1000, hiding his identity as the Necromancer of Dol Guldur. He policy of attack was to weaken the Dunadan and to recover the One Ring. He did the first successfully and the second was nearly successful by his discovery of the existence of the Ring and the ensuing chase for the Ringbearer, Frodo Baggins. The War of the Rings (which was discussed in The Lord of the Rings) in TA 3019 effectively crushed him that he can never take form again.

The Third Age ended with the Last Riding of the Keepers of the Ring on September of TA 3021 when many of the Elves and all of those who had kept a Ring of Power journeyed from Rivendell to the Grey Havens to sail over the Seas.

Fourth Age: The Age of the Dominion of Men
The Fourth Age started with the passing over the Sea of the Eldar and the Keeper of the Rings on September, TA 3021, although the first day of the FoA was on March 25, TA 3021.

During this age, most Men flourished. Under King Elessar, the Reunited Kingdom prospered. Those who are hostile to them (such as the Easterlings) were subdued and those regions once on the enemy side (such as Umbar) were now controlled by the Reunuited Kingdom. Ithilien became a separate province with Faramir being made the first Prince of Ithilien. Rohan had thrived under King Eomer during the FoA. With the Oath of Eorl renewed, the ties between Rohan and Gondor grew closer than ever.

Erebor and Dale retained their independence but were closely aligned with the Reunited Kingdom. Dwarves had also established a kingdom in Aglarond, with Gimli as the Lord of the Glittering Caves.

On FO 17, the Shire was declared a Free Land, protected by the King and that no Man can enter the region. Later, in FO 32, the Shire was extended, with Buckland and Westmarch added to it.

With the exemption of the Woodland elves in Thranduil’s kingdom or the few remaining in Rivendell , most of the Elves in ME, especially the Eldar had passed over the sea. The other races not of Men (such as Ents which had remained in Fangorn Forest) dwindled or hid themselves for they were no longer understood by Men.