Charles was the eldest son of Philip the Handsome and Joanna the Mad. His grandmother was Isabella I of Castile. As the heir of three of Europe's leading dynasties—the House of Habsburg of the Habsburg Monarchy; the House of Valois-Burgundy of the Burgundian Netherlands; and the House of Trastámara of the Crowns of Castile and Aragon—he ruled over extensive domains in Central, Western, and Southern Europe; and the Spanish colonies in the Americas and Asia.