Languages of Catalonia
The main cause of Spanish and Catalan social bilingualism in modern Catalonia was large-scale migration from the rest of Spain during the 20th century, as Catalonia started a significant industrialization which demanded an increased workforce from elsewhere. Spanish has historically been spoken among a minority of civil servants born in other regions in Spain and among segments of the wealthiest bourgeoisie. Spanish has also been spoken as a second language by most Catalans, as it has been the only official language over long periods since the eighteenth century.
Principality of Catalonia
By the 9th century, Catalan had evolved from Vulgar Latin on both sides of the eastern end of the Pyrenees. From the 8th century on, the Catalan counts extended their territory southwards and westwards, conquering territories then occupied by Muslims, bringing their language with them. In the 11th century, feudal documents written in macaronic Latin begin to show Catalan elements. By the end of the 11th century, documents written completely or mostly in Catalan begin to appear, like the Complaints of Guitard Isarn, Lord of Caboet (ca. 1080–1095), or The Oath of peace and truce of count Pere Ramon (1098).
Catalan lived a golden age during the Late Middle Ages, reaching a peak of maturity and cultural plenitude, and expanded territorially as more lands were added to the dominions of the Crown of Aragon. Examples of this can be seen in the works of Majorcan Ramon Llull (1232–1315), the Four Great Chronicles (13th-14th centuries), and the Valencian school of poetry which culminated in Ausiàs March (1397–1459). Catalan became the language of the Kingdom of Majorca, as well the main language of the Kingdom of Valencia, particularly in coastal areas. It was also extended to Sardinia and it was used as an administrative language in Sicily and Athens. Between the 13th and 15th centuries this language was present all over the Mediterranean world, and it was one of the first basis of the Lingua Franca