The proper term is Men of Twilight (as opposed to the Gondorians, High Men, and the Haradrim and Easterlings, Men of Darkness). The name reflects the Gondorian political attitude towards them: Not enemies, but also not as "noble" to be counted among themselves, hence "Middle" Men.
Most Middle Men had kinship with the Houses of Bëor or Marach. There were also Men in Middle-earth related to the Second House, the Haladin — Men of Enedwaith and Minhiriath, later to be known as the Dunlendings. But because they spoke a language that was unknown to the Númenóreans they were not at first recognized as Middle Men.
The ancestors of the Beorians fled first and the ancestors of the Hadorians learned that only afterwards and followed on their trail through the Misty Mountains in the North (close to the dreadful Iron Mountains). Many sub-tribes of both peoples stayed behind, and when the shrinking teams (now led by Bëor and Marach) reached Beleriand, those who stayed behind occupied many parts of Eriador and northern Rhovanion. These appear to be akin to the House of Hador.
In Eriador the Men began to concentrate about Lake Evendim, in the North Downs and the Weather Hills, and in the lands between as far as the Brandywine, west of which they often wandered though they did not dwell there. Some were either in Eriador, some settled, some still wandering, or else had never passed the Misty Mountains and were scattered in eastern Rhovanion.
In the Second Age the Middle Men stayed in contact with Lindon, and were friendly with the Elves and those led by Galadriel and Celeborn for a while dwelt in the country about Lake Evendim side by side with the Middle Men. However generally the Men held them in awe and close friendships between them were rare. Also they feared the Sea and would not look upon it.
 Second Age
When the Númenóreans returned to the coasts of Middle-earth in S.A. 600 in Lindon and met with Gil-galad. The news spread swiftly and the Middle Men in Eriador were filled with wonder. The sailors met with twelve messengers on the Tower Hills. They found a people who spoke languages which were distantly related to the Númenórean tongue, Adûnaic. Númenórean scholars declared that this was because these Men were descendants of the fathers of the Edain, the Atanatári, who had not crossed the Ered Luin and entered Beleriand during the First Age. The Númenóreans set up friendly relations with them, and declared them to be Middle Men, as opposed to the High Men (the Edain) or the Men of the Shadow, meaning those hostile to Númenor or in the service of Sauron.
The Númenóreans began to cultivate their new friends who were into their Dark Years, grown weak and fearful, and taught them agriculture, stonecraft, smithying and their language Adûnaic. The Middle Men were comforted, populated the western shores. They revered the memory of the tall Sea-kings whom they remembered as gods hoping each time for their return
Aldarion's successors continued his works and wrecked the banks, the shorelines, great tracks and roads whom they drove into the forests northwards and southwards from the Gwathló pushing into Minhiriath and Enedwaith, establishing themselves inland as far as the river Glanduin, the southern boundary of Eregion.
Sauron recruited pre-Númenóreans and in the early second millennium he increased pressure on the West, left his stronghold in Rhûn and relocated in Mordor, drawing closer to the Númenórean sphere of influence. His regular troops attempted to conquest Eriador, hunting and killing Middle Men and the Elves and by S.A. 1700 had mastered all Eriador, up to the River Lhûn and besieged Rivendell. Eriador was already ruined when the Númenórean fleet sent by king Tar-Minastir catched Mordor's troops in the rear and utterly defeated them, but brought peace in the Westlands had peace.
As the shadow spread over Númenor, Tar-Ciryatan sailed to Middle-earth, bringing numerous treasures back to Númenor. Later more lands were occupied, plundered or forced to pay heavy tribute in return for the lives of their inhabitants. Because of these acts they were looked upon in fear, called the "Death" itself and the Men of Middle-earth trembled at the sight of a mighty Númenórean ship on the waters of Belegaer.
 Third Age
The Northmen of Rhovanion were counted as Middle Men, as were most people living in Eriador. During the Third Age the term Middle Men was still applied to the Men of Bree, and the remaining Northmen, such as the Men of Dale and Esgaroth the Lake-town, and of course the Rohirrim. King Valacar of Gondor became so friendly with the Middle Men of Rhovanion that he married Vidumavi, a princess of the Northmen, and his son Eldacar was of mixed blood. This led to the disastrous Kin-strife of Gondor.
However hostility developed between the Middle Men of the Haladin branch and the Númenóreans, which would endure until the end of the Third Age.
 See also
- ↑ 1.0 1.1 1.2 1.3 J.R.R. Tolkien, Christopher Tolkien (ed.), The Peoples of Middle-earth, "Of Dwarves and Men"
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "Cirion and Eorl and the Friendship of Gondor and Rohan"
- ↑ 3.0 3.1 J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "Aldarion and Erendis: The Mariner's Wife"
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The History of Galadriel and Celeborn"
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Peoples of Middle-earth, "Of Dwarves and Men"
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Akallabêth: The Downfall of Númenor"
- ↑ 7.0 7.1 7.2 7.3 J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The History of Galadriel and Celeborn"
- ↑ J.R.R. Tolkien, The Lord of the Rings, Appendix F, "The Languages and Peoples of the Third Age"