The Kingdom of León (; Leonese: Reinu de Llión, , , , ) was an independent kingdom situated in the northwest region of the Iberian Peninsula. It was founded in AD 910 when the Christian princes of Asturias along the northern coast of the peninsula shifted their capital from Oviedo to the city of León. The County of Portugal separated to become the independent Kingdom of Portugal in 1139 and the eastern, inland part of León was joined to the Kingdom of Castile in 1230.