The Spanish language, also known as Castilian, has a rich and complex history that stretches back over a thousand years. Here’s a brief overview of its evolution:

1. Latin: The Spanish language has its roots in Latin, the language of the Roman Empire. Latin was brought to the Iberian Peninsula by the Romans in the 3rd century BC.
2. Visigothic: The Visigoths, a Germanic tribe, conquered the Iberian Peninsula in the 5th century AD and introduced their own language, which had an impact on the development of Spanish.
3. Mozarabic: During the Islamic conquest of the Iberian Peninsula in the 8th century AD, Arabic became the dominant language in the region. However, a Christian minority continued to speak a form of Latin known as Mozarabic.
4. Castilian: In the 9th century, a language known as Castilian began to emerge in the region of Castile, in northern Spain. It was heavily influenced by both Latin and Mozarabic.
5. Standardization: In the 13th century, King Alfonso X of Castile sponsored the creation of a standardized version of Castilian, which became the official language of the court and eventually spread throughout the kingdom.
6. Expansion: In the 15th and 16th centuries, Spanish explorers and colonizers brought the language to the Americas, where it evolved into several regional dialects.
7. Modernization: In the 18th and 19th centuries, Spanish underwent a period of modernization, with the publication of grammars, dictionaries, and other works aimed at standardizing the language.

Today, Spanish is one of the most widely spoken languages in the world, with over 500 million speakers. It has continued to evolve, with regional variations and influences from other languages, but remains one of the most important cultural and linguistic legacies of the Iberian Peninsula.