The territory that comprises the Montaña de Riaño L.A.G. is located in the northeastern part of León Province and is nestled in the Cordillera Cantábrica, which gives it a mountainous terrain.

The region has an area of 2,685.5 km² and a population of 19,459 inhabitants spread out across the 25 municipalities that make up the territory: Acebedo, Boca de Huérgano, Boñar, Burón, Cistierna, Crémenes, Cubillas de Rueda, La Ercina, Gradefes, Maraña, Oseja de Sajambre, Posada de Valdeón, Prado de la Guzpeña, Prioro, Puebla de Lillo, Reyero, Riaño, Sabero, Santa Colomba de Curueño, Valdelugueros, Valdepiélago, Valderrueda, La Vecilla, Vegaquemada, and Vegas del Condado.