The Principality of Tarragona was a state that existed in and around the city of Tarragona on the northeastern side of the Iberian peninsula from its founding by the Norman adventurer Robert d'Aguilo I (also known as Robert Bordet or Robert de Culley) in 1129 until its ultimate absorption into the Crown of Aragon in the 1170s following two decades of civil war. The state was founded after the permanent conquest of Tarragona by Christian forces during the Reconquista in 1128.