County of Barcelona
The County of Barcelona (, ) was originally a frontier region under the rule of the Carolingian dynasty. In the 10th century, the Counts of Barcelona became progressively independent, hereditary rulers in constant warfare with the Islamic Caliphate of Córdoba and its successor states. The counts, through marriage, alliances and treaties, acquired the other Catalan counties and extended their influence along Occitania. In 1164, the County of Barcelona entered a personal union with the Kingdom of Aragon. Thenceforward, the history of the county is subsumed within that of the Crown of Aragon, but the city of Barcelona remained preeminent within it. Within the Crown, the County of Barcelona and the other Catalan counties developed a common polity known as the Principality of Catalonia.