Jaca is a city of northeastern Spain in the province of Huesca, located near the Pyrenees and the border with France. Jaca is an ancient fort on the Aragón River, situated at the crossing of two great early medieval routes, one from Toulouse to Santiago de Compostela and Pau to Zaragoza. Jaca was the city out of which the County and Kingdom of Aragon developed. It was the first capital of the Kingdom of Aragon until 1096 and also the capital of Jacetania.

The Kingdom of Aragon was a medieval and early modern kingdom on the Iberian Peninsula, corresponding to the modern-day autonomous community of Aragon, in Spain. It should not be confused with the larger Crown of Aragon, which also included other territories—the Principality of Catalonia, the Kingdom of Valencia, the Kingdom of Majorca, and other possessions that are now part of France, Italy, and Greece—that were also under the rule of the King of Aragon, but were administered separately from the Kingdom of Aragon.