The Lefnui was a shallow and swift river of Anfalas in western Gondor. The Lefnui rose near the gold mines in the highlands and skirted the southern slopes of the hills until it reached the Great Sea by Andrast. The Nan Lefnui (S. "Vale of Lefnui') proper was reckoned to extend as far upriver as the town of Annon Wain and the neighboring fort of Saerthondost, after which it became the Nan-i-Feryn. Bounded by the White Mountains of Andrast to the west and north, and the Pinnath Gelin of Anfalas to the east and south, the Nan Lefnui was populated primarily by wandering Dunir clans.