During the latter half of the Years of the Trees and the First Age, the Nandorin and Avarin Elves populated the forest between the Misty Mountains and the Far East lands, mixing themselves together becoming Silvan Elves or Wood-elves. It is not known how they lived but it is possible they lived in small tribal groups wandering the forest.
After the War of Wrath and the destruction of the Beleriand, Oropher, a Sindarin prince formerly of Doriath who chose to stay in Middle-earth, came to the forest known as Greenwood the Great. He and his company were well received and well accepted as they had once lived with King Thingol, whom they regarded as distant kin. The Sindarin company intended to live like the Wood-elves: natural and undisturbed. This notion was appealing to the Wood-elves and Oropher was soon named their king, adopting their language and way of life.
After being named King of the Woodland Realm, Oropher established his capital on Amon Lanc in the southern part of the forest. The Woodland realm flourished in peace with its boundaries unchanged and way of life undisturbed for over a millennium. Sometime after SA 1000, Oropher had his capital moved further north in around the Mountains of Mirkwood (Emyn Duir). The main reason for this was the growing threat of Sauron in the East. Oropher and his people also felt threatened by the Dwarves of Khazad-dûm and by the presence of Celeborn and Galadriel in the forest. Despite these problems, the elves of the Woodland Realm still continued to roam the south of the forest westward down the Anduin.
Over one hundred years after the Downfall of Númenor, the threat of Sauron once again grew into a very real threat to Middle-earth. Oropher and the Elves of Lórien under Amdír both agreed that peace could not be resorted until Sauron was completely defeated. A sizeable army was created and a combined force of Wood-elves and Galadhrim marched to support the Last Alliance of Elves and Men. Though they were as determined to defeat Sauron as the others, Oropher and Amdír's army was lightly armed and less experienced in major warfare. They also refused to submit to the supreme authority of Gil-galad due to past disputes with Ñoldor, and so fought independently. They suffered heavy losses and Oropher and Amdír were both killed. Oropher's son survived the war and took his father's place as King of the Woodland Realm.
Despite the heavy losses their people had suffered during the War of the Last Alliance, the elves of the Woodland Realm survived and continued living peacefully in the forest for the next millennium. The peace was broken in TA 1050 when a mysterious being known as the Necromancer began living in the abandoned halls of Amon Lanc. Afterwards, the forest became dark and tainted, infested with orcs, Giant Spiders, and other mysterious and savage beings. The elves were then forced to remove themselves to the northernmost part of the forest. All settlements in the Mountains of Mirkwood were withdrawn and the capital and realm's people relocated to a cave settlement under a wooded hill, in the northeastern border of the forest. From then on, the Woodland Realm remained confined to the north. It was at this time that the elves renamed the forest to Mirkwood along other with other places they formerly occupied.
The elves of the Woodland Realm survived but lived more cautiously considering the increased danger. They traded with the neighboring realms of the Lonely Mountain (Erebor) and Dale. This however was not to last as the elves, Rhovanion and much of Middle-earth was affected by bad weather culminating in the Long Winter of TA 2758 and TA 2759 and the Fell Winter of TA 2911 - TA 2912, during which extreme cold and large blankets of snow plagued the lands. However, the most devastating blow to the Woodland Realm until the War of the Ring came in TA 2770 when the dragon Smaug came down from the North and destroyed both the Dwarves of the Lonely Mountain and the Mannish town of Dale. Afterwards, the elves moved about the forest in secret and were very distrustful of any strangers and their only contact with the outside world was trade and occasional visitation with the refugees of Dale living in Laketown on the Long Lake. It was probably during this time that the elve made the Forest Path which ran across the northern forest as the only safe passage, as the main road that ran through was no longer safe.
In TA 2941, Thorin and Company came through the Woodland Realm on their way to the Lonely Mountain on The Quest of Erebor. Thranduil considered them trespassers and had them imprisoned save for Bilbo, who remained invisible with the use of his Magic Ring, who later released them. After the death of Smaug, Thranduil offered relief to the Men of Laketown for Bard’s valiant slaying of the dragon and assembled an army to claim part of the treasure, but Thorin refused to share it and so both parties prepared for war. Bilbo tried to help the situation by delivering the ancient artifact known as the Arkenstone to the Elves and Men.
The situation did not improve and with arrival of Dáin II Ironfoot it seemed as if the Elves and Men would fight the Dwarves, but the timely arrival of Gandalf with a warning of an army of Goblins and Wargs coming to do battle for the treasure changed everything. The Elves, Men, and Dwarves were forced to join forces and fight a common enemy. The Wood-elves and their allies, including the late-arriving Eagles, defeated the orcs and many lay dead, but peace finally returned to the region with the orcs defeated and news of the White Council having driven the Necromancer out of Dol Guldur.
Peace for the elves of the Woodland Realm reigned for decades until Dol Guldur once again was inhabited by evil creatures and Mordor grew in power and influence. The Woodland Realm became involved directly in the War of the Ring when the creature Gollum was captured by Aragorn and imprisoned there, but an orc raid allowed him to escape. Afterwards, Thranduil sent his son Legolas to Rivendell as a representative of the Woodland Realm and to inform the Council of Gollum’s escape.
The Woodland Realm was attacked on March 15, 3019 by forces from Dol Guldur, becoming part of the Battles of the North. Thranduil and the Wood-elves were victorious and the forest was eventually cleansed of all its enemies and as Galadriel had thrown down the walls Dol Guldur, there was no longer any threat from there and the shadow was permanently removed from the forest. On April 6, 3019, Thranduil met with Celeborn and both agreed to rename the forest Eryn Lasgalen (Wood of Greenleaves). Soon after the war, the forest was divided with Thranduil left to rule most of the northern part.
The Woodland Realm people played an important role during the early years when a group of elves from the Woodland Realm led by the Legolas traveled to Gondor and helped rebuild the city of Minas Tirith and replenished and beautified the war-ravaged lands of Ithilien. It is presumed that the realm prospered but like the other non-mannish realms it most likely became isolated and unto itself. Its fate is unknown but as many elves left Middle-earth during the Fourth Age and the dominion of man was at hand, the Wood-elves of the Woodland Realm may have eventually become hidden and ultimately invisible to the eyes of men.
- Unfinished Tales: The History of Galadriel and Celeborn pgs. 258-59
- Unfinished Tales: The Disaster of the Gladden Fields, Notes pgs. 280-81
- The Atlas of Middle-earth pgs.39-40, 53, 62-3, 76, 107, 150, & 176