THE SECOND AGE
Earendil had two sons, Elrond Halfelven and Elros Halfelven. Elros chose to become mortal and was a bigtime king of Men, and Elrond of course was immortal and hung out in Rivendell for thousands of years. Elros pulled together the surviving Edain after the big battle with Morgoth, and led them to a new island that the angels constructed for them, the Island of Numenor. The angels had just one condition, which was that the Men not sail out of sight of land, and especially not try to sail West and find the Undying Lands.
Cut forward a few thousand years, and the Numenoreans have become a terrific Atlantean type civilization, sailing around like nuts and having a grand time. The descendants of the remaining Elves in Middle-Earth, the ones who didn’t return to the Undying Lands at the close of the First Age, they spend all their time making war on the remnants of the Enemy, which is to say, Morgoth’s sidekick Sauron. There’s a lot of back and forth and battling between the Elves and Sauron; we won’t find this out until Appendix B, but this was the era when Sauron disguised himself as a wandering jeweler (Covetous Shen?) and hooked up with some crafts-elves and created the various Rings of Power. The Numenoreans meantime explored Middle-Earth and built colonies, and eventually the Eldar recruited them to work together and fight Sauron and beat him back.
Afterwards the Numenoreans found themselves with colonies all up and down the coast of Middle-Earth, one of which survived and became Gondor. And these colonial Numenoreans at first got along great with the Men who were already in Middle-Earth, the proto-Rohirrim and the proto-Breelanders and the proto-Lake-Town-men and so on, but gradually it became less about teaching them about the angels and trading with them, and more about subjugating them. The Numenoreans got arrogant, and resentful of how they weren’t allowed to visit the Undying Lands, and their relations with the Elves soured.
Eventually you had two political parties, more or less, among the Numenoreans: the minority Faithful, who liked Elves and obeyed the angels and got along well with the other Men, and the majority Faithless, who resented Elves and angels and liked conquest. The island of Numenor itself was a bastion of the Faithless, and the mainland dominated by Faithless with pockets of Faithful. Sauron was still out there, quietly rebuilding and distributing his Rings of Power and recruiting warriors, rulers, and sorcerers of unspecified gender and Numenorean ancestry to wield the Nine Rings and eventually become his immortal wraith-slaves, the Nazgul (probably Sauron didn’t mention the part about eternal enslavement, when he was giving away the rings).
The last King of Numenor, Ar-Pharazon, was the head of the Faithless faction and came to the throne by usurping it. Ar-Pharazon waited until his Faithful uncle the king died, and seized the throne from his daughter, also Faithful, who should have become a ruling Queen. Numenorean society sounds fairly patriarchal, but they had a nontrivial number of ruling queens in their history.