Hyperdialectism describes the act of pronouncing words or phrases within a dialect that exaggerates the qualities distinguishing that particular style of speech from those around it. The current work explores literary evidence of hyperdialectism in El Cantar de Myo Çid (The Song of My Cid), the oldest preserved epic poem of Castile that portrays the adventures of a fictional Castilian hero in the time of the Iberian Reconquista. At the time of its circulation, circa 1200 CE, Castile served as a buffer state between Asturias-León and Aragon, which contributed to the economic and social hardships faced by the Castilian people. The negative stereotype associated with Castile resulted in general disdain toward Castilian dialect; however, with the rise of The Cid came exaggerated uses of linguistic characteristics that distinctively underlie the Castilian dialect, thereby evidencing a rising sense nationalism as a result of fictional creation. Possible explanations and areas for future study are also discussed.