The Spanish Kingdom, Ancient, was composed of four main regions: Navarre (7 letters), Leon (4 letters), Aragon (6 letters) and Castile (7 letters). These regions were united in the 15th century under the rule of the Catholic Monarchs, Isabella I of Castile and Ferdinand II of Aragon. Navarre was a kingdom located in the Pyrenees Mountains, while Leon was a kingdom located in the northwest of the Iberian Peninsula. Aragon was a medieval kingdom located in the northeast of the Iberian Peninsula, and Castile was a kingdom located in the central part of the peninsula. Together, these four regions formed the Spanish Kingdom, Ancient.