The Years of the Sun and the First Age

What we actually know as the Ages of Lord of the Rings’ history are collectively known, like the periods before them, as the Years of the Sun—it’s actually the time frame in which those two celestial bodies first existed. The First Age itself is just the first chapter, just under six hundred years, in much of which Melkor (now known as Morgoth!) holds dominance over the realms of Middle-Earth. Men first appear on the continent during this period, and it is marked by the appearance of the Noldorian exiles in Middle-Earth, the Elves who had traveled to Aman during the Years of the Trees who pursued Morgoth after he destroyed them and stole the powerful jewels containing remnants of Laurelin and Telperion’s light, the Silmarils.
Forming an alliance with the Sindar elves that remained in Middle-Earth’s Beleriand region, the three tribes of Men (collectively known as the Edain), the Dwarves, the Noldor, and a host of Valar and Maiar went to war with Morgoth in a battle known as the War of Wrath. This culminated in Morgoth’s destruction and cataclysmic damage to Middle-Earth, with much of Beleriand sunk into the ocean, and untold death, including the near-decimation of the Edain.