Catalan
The Catalans are the people of the eastern Pyrenees and the Mediterranean littoral of the peninsula, whose Romance speech evolved from Vulgar Latin by the 800s and slowly diverged from Old Occitan between the 1000s and the 1300s. When the County of Barcelona broke from the Carolingian Empire in 988 it became the heart of an expanding principality, and conquests of the 1200s carried the language into the new kingdom of Valencia and beyond.
The later Middle Ages were Catalan's golden age: Ramon Llull of Majorca, who died in 1315, wrote philosophy, science and fiction in Catalan, the royal chancery forged a standardized tongue that served as an official language of Sicily and Sardinia, and Martorell's chivalric romance Tirant lo Blanc appeared in 1490.
After the union with Castile in 1479 the court turned to Spanish, and the Nueva Planta decrees of 1714 imposed Castilian in law and administration, while the Treaty of the Pyrenees in 1659 had already left the Catalans of Roussillon under France.