Due to several historical events, such as the 15th century dynastic union of Spain between Isabella I of Castile and Ferdinand II of Aragon, as well as the early 16th century invasion and annexation of Navarre by Ferdinand II of Aragon, the title lost its importance. This was exacerbated when the Kingdom of Navarre ended up divided between the Kingdom of France and the Kingdom of Spain. While the title "Prince of Viana" has recently been revived, Viana itself no longer provides the heir with an income. Rather, it symbolizes the historical continuity of the former Crown of Navarre within the united Spanish monarchy.