Numenore

The Edain, first to waken among the race of humans, had joined the elves and host of the Valar in their conquest of Morgoth. In gratitude, the Valar raised the Isle of Numenore 900 miles off the western coast of Endor as a gift to them (SA 32), and granted them and their descendants long life far beyond that of the other races of Man. The one ban placed on them was never to sail West to the isle of Aman. The star shaped Numenore was marked by Meneltarma, its central mountain, from which it is said Tol Eressea could be seen on a clear day. Each arm of the star descending from Meneltarma had its own unique geography and features. The first king was Elros, brother to Elrond Half Elven. A rich Edain culture developed among the Men of the West, with Elves visiting often from Tol Eressea in the West and heavily influencing Numenorean development. Six centuries after its establishment, Numenoreans returned to Endor and began exploring the Western Coast. They made contact with indigenous men and instructed them in agriculture and building as they built settlements along the Western Coast of Endor.
As time passed, a political and philosophical divide began to grow among the Numenoreans. Many began to resent the Ban of the Valar and believed the immortality of the Elves was tied to their ability to walk the shores of Valinor as Men were not allowed to do. Their exploration of Endor began to change to colonization and conquering in some areas, exacting tribute and displacing indigenous races of men from their lands. The more powerful they became and the more superior they believed themselves to be the more their sense of entitlement to all of Arda, including the Blessed Realm, grew. As Sauron’s power grew in Mordor, the Numenoreans built two fortresses nearby: Pelargir up the Anduin River and Port of Umbar further south. The fortresses represented the political divide growing among the Men of the West.
Eventually, Sauron proclaimed himself King of Men, which the King of Numenore took as a personal challenge. He began construction of an invasion fleet and sailed to Endor, laying siege to Mordor. Sauron surrendered and was taken as prisoner back to Numenore, where he remained captive over 50 years. This allowed Sauron the access to the King’s ear he craved, and he used his powers of persuasion to deepen the distrust of the Valar and Elves already growing. Eventually, worship of the Valar was banned as was the Elven language. And then Ar Pharazon, the last king of Numenore, sailed with is fleet to Aman.
Those ships that sailed were destroyed as soon as they landed. And the Valar Ulmo caused the island to sink, taking back what he had once given. The Dunedain (the faithful), however, were warned in time to flee to Endor in nine ships led by Elendil. Elendil founded the kingdoms of Arnor and Gondor in the Northwest. Elendil ruled Arnor while leaving the rule of Gondor to his sons Isildur and Anarion. The Dunedain built Orthanc at Isengard to as a stronghold and link between the two kingdoms
In the Fourth Age, two gods of the sea battled as Ulmo of the Valar sought to keep what he had claimed and Orium of the First sought to wrest it from him. In the end, Orium prevailed and Numenore was raised from its depths. The God King Sehan, who carried Numenorean blood through his human heritage, claimed it for his own and for any of the Numenorean race who wished to return and swear fealty to him. While his occupation of Gondor and his expansion of the Numenorean Empire in Endor has ended, he still resides on Numenore along with those loyal to him.