From The Lord of the Rings wiki
Arnor
Arnor was the northern kingdom of the Dúnedain in Middle-earth, founded by Elendil following the downfall of Númenor.
History of the North-kingdom
Arnor was established in the year 3320 of the Second Age by Elendil, who led the faithful Númenóreans to the shores of Middle-earth. It served as the sister realm to Gondor in the south, with its capital city situated at Annúminas on the shores of Lake Evendim. The kingdom flourished for centuries, maintaining the line of the High Kings who held the Sceptre of Annúminas.
Decline and Legacy
Following the death of King Eärendur, the kingdom suffered from internal strife and was eventually divided into three smaller states: Arthedain, Cardolan, and Rhudaur. These successor states were systematically dismantled by the Witch-king of Angmar, leading to the eventual collapse of the northern realm. By the time of the War of the Ring, the land was largely desolate, inhabited by the Rangers of the North who protected the remnants of the Dúnedain.
Restoration
The legacy of Arnor remained vital to the history of Middle-earth, as the bloodline of the kings survived through the Chieftains of the Dúnedain. This lineage culminated in the return of Aragorn, who was crowned King of the Reunited Kingdom after the defeat of Sauron. His ascension marked the restoration of the ancient realm, bridging the gap between the lost glory of the North and the new era of peace witnessed by Frodo Baggins, Gandalf the Grey, and their companions.
