One of the two great divisions of the descendants of the Númenóreans in Middle-earth (the other being the Gondorians of the South-kingdom). The North-kingdom of Arnor had originally held the capital of High King Elendil at Annúminas, and the Dúnedain of that land were ruled for centuries by the descendants of Elendil's elder son Isildur.
Before the end of the first millennium of the Third Age, the land of Arnor fell into dispute between the sons of King Eärendur, and the Dúnedain who lived there became divided into three realms: Arthedain, Cardolan and Rhudaur. One by one, these kingdoms fell, until at last the Dúnedain of Arnor had become a dwindled and wandering people. Nonetheless, their chieftains maintained the bloodline of Elendil's eldest son, and Aragorn - among whose titles was Chieftain of the Dúnedain of Arnor - was his direct descendant through many generations
The Two Kingdoms founded by Elendil and his sons were originally intended to form two parts of a greater nation of the Dúnedain, ruled by a High King at Annúminas. This was not to be. The loss of Elendil's son Isildur in the Disaster of the Gladden Fields led to a chain of events that separated Arnor in the north from Gondor in the south, and the two kingdoms continued to follow different paths through history.
Arnor, the North-kingdom of the Dúnedain, was ruled by the direct descendants of Isildur, beginning with Valandil, his youngest son. Though the bloodline of the Northern Dúnedain came directly from the old High King, theirs was a troubled realm. Internal strife and war with Angmar saw Arnor become fractured and eventually destroyed, leaving the Dúnedain of the North a dwindled and wandering people.
Nonetheless, the line of Isildur was maintained through the Chieftains of this people. Aragorn II was Isildur's Heir through thirty-nine generations, and it was he who reunited the Kingdoms of the Dúnedain after three thousand years of separation.
