The son of Arveleg I came early to the throne of Arthedain. While he was still in his youth (probably no more than eighteen years old), the Witch-king of Angmar launched a mighty invasion of his kingdom, that came close to destroying it. Araphor's father Arveleg fought in the defence of the Tower of Amon Sûl, and his early death in that battle brought Araphor to the throne.
Records of the events of this time are incomplete, but it seems that the Witch-king laid siege to the royal city of Fornost. The young Araphor went to war with aid from Círdan and the Elves of Lindon, and succeeded in relieving the siege and driving back the forces of Angmar.
After Araphor's defeat of Angmar, there is no record of further warfare during his long reign. Nonetheless, he ruled a diminished and dwindling people; the wars of his youth had seen the Northern Dúnedain come close to destruction. Rhudaur was now a tributary state to Angmar, and the Dúnedain of Cardolan were all but extinct.
Araphor ruled Arthedain for one hundred and eighty years, and was succeeded by his son, named for Araphor's heroic grandfather Argeleb, who ruled as Argeleb II.
The date of Araphor's birth appears only in The History of Middle-earth volume XII, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.
The Ara- of Araphor's name is a royal prefix, indicating his claim to all the lands of lost Arnor, but the -phor element is less certain. There is an Elvish root phor meaning 'right' (the direction), so possibly Araphor's name means something like 'royal right', but it's unclear whether this interpretation is the intended one.