In the 10th century, the Kingdom of Asturias gave way to the Kingdom of León, and during the Middle Ages the geographic isolation of the territory made historical references scarce. Through the rebellion of Prince Henry (the later Henry II of Castile) in the 14th century, the Principality of Asturias was established. The most famous proponents of independence were Gonzalo Peláez and Queen Urraca, who, while achieving significant victories, were ultimately defeated by Castilian troops. After its integration into the Kingdom of Spain, Asturias provided the Spanish court with high-ranking aristocrats and played an important role in the colonisation of America. Since 1388, the heir to the Castilian (later Spanish) throne has been styled Prince of Asturias. In the 16th century, the population reached 100,000 for the first time, and within another century that number would double due to the arrival of American corn.