Roussillon (rōōsēyôN´), small region and former province, S France, bordering on Spain along the Pyrenees and on the Mediterranean. It is now roughly coextensive with Pyrénées-Orientales dept. Perpignan is the historical capital. Wine, fruit, and olives are the chief products of this fertile and densely populated region, which also has a tourist industry. The area has changed hands many times, from the Romans, who arrived c.121 BC, through the Visigoths, the Arabs, the Carolingians, the Spaniards, the counts of Barcelona, and the kings of Aragón, France, and Majorca. Louis XIII conquered it from Spain in 1642, and French possession of the Catalan-speaking region was confirmed by the Treaty of the Pyrenees (1659).