Gibraltar is a British overseas territory located near the southernmost tip of the Iberian Peninsula overlooking the Strait of Gibraltar. The territory shares a border with Spain to the north. Gibraltar has historically been an important base for the British Armed Forces and is the site of a Royal Navy base. The name of the territory is derived from the Arabic name Jabal Tāriq (جبل طارق), meaning "mountain of Tariq", or from Gibel Tāriq, meaning "rock of Tariq". It refers to the geological formation, the Rock of Gibraltar, and the Berber Umayyad general Tariq ibn-Ziyad, under the orders of Caliph Al-Walid I who led the initial incursion into Iberia in advance of the main Moorish force in 711. Earlier, it was known as Mons Calpe, one of the Pillars of Hercules. Today, Gibraltar is known colloquially as Gib or The Rock.