The story of Arnor is that of a kingdom nostalgic for other eras, of a land that suffered an irretrievable decline and which Sauron’s scavenging wolves tore apart as it crumbled.
The birth of the kingdom has as its origin a disappearance. It is a clear case of “when something dies, something new is born”.
We have to go back to the peak years of Númenor, the star island that the Valar gave to the three houses of the Edain who helped in the war against Melkor. Called Númenóreans, they became the most powerful civilization of Arda after the Valar themselves, and their greed was finally punished by Eru-Ilúvatar, who, after an insult from the last king of Númenor, Ar-Pharazôn, decided to destroy the island.
The Númenórean civilization disappeared, but not his legacy. Over the centuries, Númenor had built colonies all over Middle-earth, especially along the coasts. Some of their cultures survived there, although always mixed with lesser men.
However, a small part of the Númenórean population, including a branch of the royalty, managed to avoid disaster and escape the island’s destruction. The survivors were divided into two large groups. One went south to establish Gondor, while the other, led by Elendil, founded the kingdom of Arnor.
The extent of their lands was enormous, encompassing almost the entirety of Eriador. Its borders included the elven kingdom of Lindon to the west and the Misty Mountains to the east. To the north, it bordered the lands of Angmar and part of Forochel Bay, while to the south, the Gwathló River marked its boundary.
For centuries Arnor grew and developed so much that it was reminiscent of the times of old when Númenor was the most dazzling civilization in all of Arda. However, little by little, decadence settled in the kingdom as the passage of time diluted the Númenórean blood among the inhabitants, even among its royalty.
In the eighth century of the Second Age, the tenth king of Arnor, named Eärendur, died, and his sons entered into dispute for the kingdom’s dominions. The country’s peak had long since passed, and the conflict between the three heirs led to a partition that would accelerate the degradation process.
Thus, Arnor was divided into three new independent kingdoms: Arthedain in the northwest, Rhudaur in the northeast, and Cardolan to the south. Of these, only Arthedain retained the direct lineage of Isildur, while the other two kingdoms lost their kingship to lesser lords.
What should have been a solution ended up becoming the worst of the problems since, practically, the three kingdoms were in constant mutual dispute from the very beginning.
They were constantly battling to gain ground and with a great motive for the conflict: the control of the watchtower of Amon Sul, which guarded one of the seven Palantir that survived the destruction of Númenor.
The kingdom of Rhudaur was, from the beginning, the most belligerent and chaotic of the three kingdoms, so only five centuries after its foundation, it fell under the influence of the kingdom of Angmar. It was a dark place reigned by the Witch-king of Angmar, Sauron’s lieutenant (determined to destroy the Númenórean descendants both in the north and the south).
Thus, in T.A. 1350, both kingdoms officially became allies and started the all-out war against Arthedain and Cardolan, who allied to fight their enemy. The war that began would last for centuries, although Cardolan would barely resist for fifty years and would be conquered in T.A. 1409.
Arthedain was isolated and facing three kingdoms led by Angmar, who kept growing in power thanks to the troops Sauron sent from Mordor, thousands of orcs, and dark creatures roaming all over Eriador, causing havoc without rest.
Thanks to the direct lineage of Isildur and its good relationship with Rivendell and Lindon, the kingdom of Arthedain managed to resist for five centuries more, always in the minority and with much suffering, side by side with the elves. However, the alliance was not enough, and Arthedain finally succumbed to Angmar in T.A. 1974, when Arvedui, its last king, died on the battlefield.
In that last disastrous stage of the war, Gondor sent an army to help Arthedain, although it arrived too late. However, that same army allied with the remnants of the vanished kingdom and, together with the elves led by Círdan, defeated the Witch-king near Fornost (Arthedain’s former capital).
Although the victory meant the disappearance of the kingdom of Angmar, nothing could be saved from the descendant realms of Arnor, and the once great country of the north disappeared forever.
However, his legacy did not disappear completely, for Arvedui’s son became the first leader of the Dúnedain of the North, heirs to the lineage of Isildur despite having no kingdom to rule. They abandoned the ruins of the cities and went to live in the forests, secretly protecting all the lands that were once part of Arnor.
In their shadowy task, they were aided by the elves of Rivendell, who knew their true lineage and believed that as long as there was hope, the kingdom of Men could rise again.
Many more centuries had to pass, until practically the fourth millennium of the Third Age, for Isildur’s lineage to re-emerge more vigorously than ever. It was when Aragorn II, after his pivotal role in the War of the Ring, restored the ancient kingdom of Arnor as part of the Reunited Kingdom.
Annúminas, the kingdom’s first capital, was rebuilt and became once again a majestic city, the most important in all of northern Middle-earth.