The End of the Third Age
When Gollum fell into the Cracks of Doom, with the One Ring, he and the Ring were destroyed, and most importantly, so was Sauron's strength which he had passed into the Ring. Thus was Sauron's influence from the world taken away.
The Third Age ended when the Ring was destroyed: the evil empire of Sauron collapsed, and the other Rings of Power were put to rest, and the last legitimate heir to the throne of Gondor was crowned.
With the end of the War of the Ring peace and prosperity returned to Middle-Earth. yet at the same time it was ordained that the last of the great Elvish powers should pass from mortal lands. The last of the good and the great amongst those people - along with some chosen of the Fellowship of the Ring - took the Elven ships out over the Straight Road and sailed westward to the Undying lands.
