What is "castilians"

Castilians (Spanish: castellanos) are certain inhabitants in regions of central Spain including at least the eastern part of Castile and León, the northern and eastern parts of Castile-La Mancha, and the Madrid community, who are the source of the Spanish language (Castilian) among other aspects of cultural identity. However, not all people in the regions of the medieval Kingdom of Castile think of themselves as Castilian. For this reason, the exact limits of what Castile is today are disputed.

Through the Reconquista and other conquests in the Middle Ages, the Kingdom of Castile (later Crown of Castile) spread over a large part of the Iberian Peninsula, especially towards the southern Spanish regions. After this, since the 15th century, through the Spanish colonization of the Americas, the Castilians also spread over the New World, bringing with them not only their language, but also elements of their culture and traditions.