 Os Ancares has mountain valley high altitudes and steep slopes located in the northwest of El Bierzo.The main river that gives name to the region is the Ancares river, a tributary of the river Cúa which, in turn, is of the Sil.This river began as Cuiña and has tributaries from the rivers Miravalles and de la Vega and streams from Penedón, Baliñas and the Cross.