Umbar is the largest coastal port in Middle Earth being the center of trade throughout the Hither Lands. The men of Umbar, known around Middle Earth as the Corsairs of Umbar, were known throughout the known world as the greatest mannish ship builders and sailsmen.
During the Kin-Strife, Umbar joined an alliance with the Line of Castamir in an attempt to overthrow Eldacar and place true Númenórean blood on the throne of Gondor. Castamir promised the lands of Harondor in return for Umbar's loyalty, of which he would deliver at cease of Eldacari support. The Corsairs of Umbar were not used prpredominantly in the Kin-Strife as a sea-faring force due to the Traditionalist League holding all major Gondorian ports, but rather as a land force that can dock almost anywhere from coasts to rivers.