The history of the Spanish language and the origin of the dialects of Spain begin with the linguistic evolution of Vulgar Latin. Castilian & Andalusian dialects emerged in the Iberian peninsula (Hispania) during the middle ages.The emergence of modern Spanish more or less coincided with the reconquest of Moorish Spain which was completed by Isabella of Castile & Ferdinand of Aragón.

Spanish is one of the Romance languages in the Italic subfamily of the Indo-European language family, and within Spain, and has two major dialects: Andalusian and Castilian. Many other dialects exist in other geographical areas, namely North and South America.

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.