The history of the Spanish language in Spain and the origin of the dialects of Spain begin with the linguistic evolution of Vulgar Latin.
The Spanish Language can be traced back to the Indo-European language family. Around 2000 years before the birth of Christ, Celtiberians spoke an early Celtic language.
The inhabitants of this region, an area later referred to by scholars as Hispania, started learning Latin from the Romans. The combination of the Celtic language and Latin evolved into what is referred to by many as Vulgar Latin. Vulgar Latin was an adapted form of Latin that used phrases and words that were different from traditional Latin.
When the Visigoths took over the region called Hispania, Latin remained the dominant and official language of the region. This continued until the Moors, an Arabic-speaking group, conquered the region. Arabic became the dominant language, except for in certain regions dominated by the Christians. In such regions, Vulgar Latin remained the official language. As the Christian groups started to reclaim Moorish Spain, Vulgar Latin returned as the dominant language in every region.
Castilian Spanish Dialect
While Vulgar Latin was dominant, it took on a different form, integrating Arabic and forms of a related dialect called Mozarabic. It is estimated that approximately 3000-4000 words in today’s Spanish are derived from Arabic.
Castilian dialects of Spanish started to take form around the 13th century with King Alfonso X, referred to as the Learned-King of Castile and Leon. Toledo became the cultural epicenter for the King and his scholars. In Toledo, these scholars created works in Castilian Spanish and then began a series of translations of the various works of science, the law, literature, history, etc. into Castilian Spanish. These translations became the basis for the dissemination of information in a significant part of Western Europe. The King soon declared Castilian as the official language for government documents and decrees.
The dominance of the Castilian dialect continued to grow as the Catholic kingdoms took over most regions of Spain. Isabella and Ferdinand declared Castilian Spanish to be the official dialect. Soon thereafter appeared the Art of the Castilian Language, a work that helped shape and standardize the Spanish language.
Castilian Spanish then quickly became the official language for all educational materials and official documents in all of Spain. Certain regions maintained different dialects, most notably Andalusian, spoken in and around Seville.