J.R.R. Tolkien gives the great island kingdom of Men in the Second Age the name Númenor.
Númenor was raised from the sea by the Valar as a reward for the Men who had aided the Elves during the wars against Morgoth. Its people, the Dúnedain, received exceptionally long lives and developed a powerful maritime civilization.
The island kingdom became increasingly divided between those who remained faithful to the Valar and those who resented the limits placed on human mortality. Under King Ar-Pharazôn, Númenor challenged Sauron and was eventually destroyed after its ruler attempted to invade Aman.
Survivors led by Elendil escaped and founded the kingdoms of Gondor and Arnor in Middle-earth. Númenor is therefore the source of the royal line later associated with Aragorn.