Some decades before Arahael assumed the leadership of his people, Gandalf had gone to Dol Guldur and driven its master into the east. The Witch-king, who had ravaged the realm of Arahael's grandfather Arvedui two generations before, was far to the south in Minas Morgul. So, Arahael led the Dúnedain during the time known as the Watchful Peace, and was untroubled by war.
The date of Arahael's birth appears only in The History of Middle-earth volume XII, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.