Editor’s Note: The following contains spoilers for Season 2 Episode 5 of The Rings of Power and some spoilers from Tolkien’s Legendarium about what happens to Númenor in the book canon.

An age-old enmity is about to be lit afire in The Lord of the Rings: The Rings of Power. In Season 2, Episode 5, “Halls of Stone,” Ar-Pharazôn (Trystan Gravelle) tells his son, Kemen (Leon Wadham), about how the shores of Valinor can sometimes be seen from Númenor. He talks bitterly, brooding over the fact that Elves will live forever in the Undying Lands, while Men have their days numbered. This anti-Elves sentiment is very present in Númenor and is growing by the day, but why exactly do the people from the star-shaped island and the Elves not get along? They once fought side by side, so what happened?

Númenor Has Its Origins Directly Tied to the Elves

Hearing Ar-Pharazôn’s remarks about the Elves, it’s hard to believe they come from similar places. The third episode of The Rings of Power‘s first season glosses over the subject. In “Adar,” Galadriel (Morfydd Clark) and Elendil (Lloyd Owen) revisit the archives of Númenor and find out about Elros, the very first king of Númenor — and Elrond’s (Robert Aramayo) brother. Elros and Elrond are both half-Elven, meaning they were blessed by the Valar with the gift of choosing whether they wanted to be Men or Elves. Elros chose to be Human, while Elrond chose to be an Elf.

However, the history between those two races goes way back before Númenor even existed. Initially, Elves and Men had good relations in the First Age. It’s during this period of Middle-earth history when there were two male Human and female Elf couples, Beren and Lúthien and Tuor and Idril — both of whom Elros and Elrond descend from. Back then, Middle-earth was bigger in space, expanding to the continent of Beleriand and populated by many Elven and Human realms.

Unfortunately, the First Age is marked by the constant confrontation between the Free Peoples of Middle-earth and the Dark Lord Morgoth. Elves and Men often fought together, but are only able to defeat Morgoth once the Valar themselves leave Valinor and join the fight, triggering the War of Wrath. The following death and destruction is so great that Erú Ilúvatar himself — the equivalent to God in J.R.R. Tolkien‘s Legendarium and creator of the Valar, the Elves, and Humans — decides to sink Beleriand completely, resulting in the current configuration of Middle-earth’s geography.

The Elves and Men are rewarded, however. The Eldar (Elves) continue to be allowed into the Undying Lands of Valinor, while the Humans who aided them become known as the Edain, and are blessed by the Valar with the Isle of Elenna, where they establish the kingdom of Númenor. The Edain are also distinguished from regular humans from Middle-earth, being granted longer lifespans and strength by the Valar. With a kingdom of their own and heightened abilities, it would seem that the Edain had reason to be content with their lot from the Valar, but that’s not how it turns out.

Sauron Plays a Big Part in Fueling the Rivalry Between Elves and Men

Early Numenóreans maintain close ties with the Elves of Eressëa in Valinor and the Elves of Middle-earth, particularly those under Gil-galad (Benjamin Walker) in Lindon. They learn a lot from the Eldar, including wisdom, craft, and knowledge of the wider world, and their friendship was considered a blessing. The early kings and people of Númenor are faithful to the Valar and maintain strong ties with the Elves, and also aid Middle-earth in its struggle against the forces of Sauron (Charlie Vickers).

This doesn’t last, however. By the latter part of the Second Age, pride and corruption began to take hold of Númenor’s rulers and its people. Numenóreans begin to resent their mortality and envy the Elves’ immortality, a sentiment Ar-Pharazôn clearly displays in “Halls of Stone.” This eventually leads to a division in Numenórean society between the Faithful, who remain loyal to the Valar and the Elves, and the King’s Men, who continue to envy and loathe them. In the books, this schism grows after Ar-Pharazôn leads Númenor in a war against Sauron in the Second Age, and brings the Dark Lord back to the star-shaped island as a prisoner. The Dark Lord soon starts deceiving Ar-Pharazôn, eventually becoming the king’s advisor. It’s under Sauron’s influence that most Edain start worshiping Morgoth, deepening the moral decay in Númenor.

Eventually, Ar-Pharazôn turns his eyes to Valinor and leads the largest armada in the world against the Valar in search of immortality. To stop this, Erú Ilúvatar himself intervenes. He sinks the Isle of Elenna just like he did Beleriand, and, to prevent further attempts by Men to invade Valinor, reshapes the world. Before this, Arda (as the planet is known) was flat, but Erú makes it into a sphere and separates the continent of Aman, where Valinor is located, from the rest of the world.

The Faithful Are All That Is Left of Númenor in Middle-earth

In the scene after Ar-Pharazôn and Kemen’s conversation, Tar-Míriel (Cynthia Addai-Robinson) and Elendil talk about the visions the Palantir showed them. Míriel has seen Númenor sinking multiple times, and is aware of the island’s unfortunate future. While she remains in retreat, Elendil and the Faithful are outlawed. In the books, he and his two sons, Isildur (Maxim Baldry) and Anárion, are able to leave Númenor with the Faithful during the cataclysm that sinks the island, and their ships are guided by a great storm sent by the Valar, which carries them to safety in Middle-earth.

Having lost everything in the fall of Númenor, the Faithful turn to the Elves for aid in their new home in Middle-earth. With their help, Elendil establishes the kingdom of Arnor in the north, while Isildur and Anárion establish the realm of Gondor in the south. By the Third Age, the Edain are now mostly gone, the Faithful being all that is left; those who descend from them are known as the Dunedáin, the most famous of them being Aragorn (Viggo Mortensen), who is born into Isildur’s bloodline and, thus, is the heir to both Arnor and Gondor.

Season 2 of The Rings of Power is streaming on Prime Video in the U.S. New episodes air weekly on Thursdays.