The Kingdom of Cardolan was one of the divisions of Arnor, founded in TA 861. Cardolan included all the land south of the Great East Road between Baranduin and Gwathlo-Mitheithel. The Dúnedain of Cardolan defended their land against Angmar until TA 1409, when the country was overrun and the surviving Dúnedain were forced to take refuge in the Old Forest or the Barrow-downs.

In this war the last prince of Cardolan was killed, but when Angmar was for a time defeated by the Elves, the people of Cardolan returned to their homes.

In TA 1636, the Great Plague killed the last of the Dúnedain of Cardolan, and large portions of the country, especially Minhiriath in the south, were depopulated. After this time Cardolan does not seem to have existed as a nation, although there were doubtless still scattered settlements there at the time of the War of the Ring.
Encyclopedia entry originally written by Buckland_Lass