Under Roman rule, in 19 BC, the region became known as Hispania, and its inhabitants learned Latin from Roman traders, settlers, administrators, and soldiers. When the classical Latin of the educated Roman classes mixed with the pre-Roman languages of the Iberians, Celts, and Carthaginians, a language called Vulgar Latin appeared. It followed the basic models of Latin but borrowed and added words from the other languages.
Even after the Visigoths, Germanic tribes of Eastern Europe, invaded Hispania in the AD 400s, Latin remained the official language of government and culture until about AD 719, when Arabic-speaking Islamic groups from Northern Africa called Moors completed their conquest of the region. Arabic and a related dialect called Mozarabic came to be widely spoken in Islamic Spain except in a few remote Christian kingdoms in the North such as Asturias, where Vulgar Latin survived.
During the succeeding centuries, the Christian kingdoms gradually reconquered Moorish Spain, retaking the country linguistically as well as politically, militarily, and culturally. As the Christians moved South, their Vulgar Latin dialects became dominant. In particular, Castilian, a dialect that originated on the Northern Central plains, was carried into Southern and Eastern regions.
Castilian & andalusianThe resulting language was a hybrid because Castilian borrowed many words from Mozarabic, and modern Spanish has an estimated 4,000 words with Arabic roots.
The creation of a standardized Spanish language based on the Castilian dialect began in the 1200s with King Alfonso X, who was called the Learned–King of Castile and Leon. He and his court of scholars adopted the city of Toledo, a cultural center in the central highlands, as the base of their activities. There, scholars wrote original works in Castilian and translated histories, chronicles, and scientific, legal, and literary works from other languages (principally Latin, Greek, and Arabic). Indeed, this historic effort of translation was a major vehicle for the dissemination of knowledge throughout ancient Western Europe. Alfonso X also adopted Castilian for administrative work and all official documents and decrees.
The Castilian dialect of Spanish gained wider acceptance during the reign of the Catholic monarchs Isabella of Castile and Ferdinand of Aragón, who completed the reconquest of Spain in 1492 by pushing the Moors from their last stronghold in the southern city of Granada. Isabella and Ferdinand made Castilian the official dialect in their kingdom. In the same year the Moors were defeated, an important book appeared: Antonio de Nebrija's Arte de la lengua castellana (The Art of the Castilian Language). It was the first book to study and attempt to define the grammar of a European language.
The Castilian dialect of Toledo became the written and educational standard in Spain, even though several spoken dialects remained. The most noteworthy was Andalusian, a dialect spoken in the southern city of Seville in the Andalucía region.