Umbar was located on the southeast coast of the Bay of Belfalas, and was known as a natural harborage for ships.

Early in the Second Age, the Havens of Umbar were used by the ships of Númenor, and in 2280 Umbar was made into a great fortress protecting the interests of Númenor from the forces of Sauron.

In SA 3261, Ar-Pharazon of Númenor landed with a great force at Umbar and from there returned to Númenor with Sauron as a prisoner. Sauron then began the corruption of the Numenorians that led to the Downfall of Numenor.

When Gondor and Arnor, the "Realms in Exile", were founded in SA 3320, Umbar was under the control of the Black Númenorians and remained loyal to Sauron throughout the early years of the Third Age.

In TA 933, Earnil I took control of Umbar and made it into a great fortress of Gondor. In TA 1015, Umbar was taken from Gondor, but in TA 1050 Hyarmendacil retook Umbar and also gained control of Haradwaith.

Umbar remained under the control of Gondor until TA 1448 when the sons and followers of Castamir fled Gondor and took control of Umbar. They became known as the Corsairs of Umbar and harried the coasts of Gondor from that time on until the end of the Third Age.

In TA 1810 Telumehtar Umbardacil took Umbar back for a time, but it was lost for good, along with all of Gondor's eastern territories, in TA 1856 during the wars with the Wainriders.

In TA 2979, a force from Gondor, led by Aragorn as Thorongil, managed to attack Umbar and destroy most of its fleet, but did not attempt to retake it.

During the War of the Ring, the Corsairs of Umbar were mostly destroyed by the ghosts of the Oath-breakers following Aragorn from the Paths of the Dead. After the destruction of the Ring, Umbar ceased to be an enemy of Gondor.