History of Catalonia
In 1137, Ramon Berenguer IV, Count of Barcelona accepted King Ramiro II of Aragon's proposal to marry Queen Petronila. Thus they united the dinasties of the County of Barcelona with the Kingdom of Aragon and they created the Crown of Aragon. Meanwhile, the County of Barcelona and the other Catalan counties adopted a common polity known as Principality of Catalonia. Catalonia contributed to the expansion of the Crown's trade and military, most significantly their navy. The crisis of the 14th century, the end of the reign of House of Barcelona and a civil war (1462–1472) weakened the role of the Principality in Crown and international affairs.