<human>:  Why was the Kingdom of Castile called Castile?
<bot>: Castile comes from the Latin word for castle. Castile was a kingdom in the Iberian Peninsula that existed from the 9th to the 15th century. Castile was one of the largest kingdoms in Europe during the Middle Ages, and it was ruled by the House of Castile. The Castilian language is a Romance language that is related to Spanish and Portuguese.