Name given to the renegade Dúnedain who fled Gondor after the Kin-strife.
In the Third Age, the dreaded Corsairs of Umbar tyrranized the coastlands of Middle-earth for many centuries. The sight of their black-sailed dromonds always filled the peoples of Middle-earth with fear, for they held many warriors and were driven by the power of slaves pulling many oars.
The Númenóreans were the founders of Umbar in the Second Age, but in time they succumbed to evil and, after the Downfall of Númenór, some remained in Umbar and were named the Black Númenóreans. They were an evil sea power. Yet in time the kings of Gondor came against them, and in 1050 (TA), the power of the Black Númenóreans was broken forever and Umbar became a fortress in Gondor's realm.
But there was always strife with the Haradrim, who often attacked Umbar, and also there was rebellion within gondor itself, until finally the rebels of Gondor, the Haradrim and those few of the scattered Black Númenóreans who remained, conquered Umbar with many great ships and restored its power. So it was from the fifteenth century until the War of the Ring, that these people were named the Corsairs of Umbar and were always counted among the chief enemies of the Dúnedain of Gondor and Arnor.
In the last century of the third Age, Aragorn proved to be the chief architect of the downfall of the Corsairs. He led a force of Dúnedain from the north, together with an army of phantoms from the Paths of the Dead into the havens of Umbar, where he slew the captain of the Corsairs and torched their fleet. And with this, the power of the Corsair was broken.