Tradition holds that Charles the Great (Charlemagne) granted a charter to the Andorran people in return for fighting against the Moors. Overlordship of the territory was by the Count of Urgell and eventually by the bishop of the Diocese of Urgell. In 988, Borrell II, Count of Urgell, gave the Andorran valleys to the Diocese of Urgell in exchange for land in Cerdanya. Since then the Bishop of Urgell, based in Seu d'Urgell, has owned Andorra.
Before 1095, Andorra did not have any type of military protection and the Bishop of Urgell, who knew that the Count of Urgell wanted to reclaim the Andorran valleys, asked for help and protection from the Lord of Caboet. In 1095, the Lord of Caboet and the Bishop of Urgell signed under oath a declaration of their co-sovereignty over Andorra. Arnalda, daughter of Arnau of Caboet, married the Viscount of Castellbò and both became Viscounts of Castellbò and Cerdanya. Years later their daughter, Ermessenda, married Roger Bernat II, the French Count of Foix. They became Roger Bernat II and Ermessenda I, Counts of Foix, Viscounts of Castellbò and Cerdanya, and also co-sovereigns of Andorra (shared with the Bishop of Urgell).
In the 11th century, a dispute arose between the Bishop of Urgell and the Count of Foix. The conflict was resolved in 1278 with the mediation of Aragon by the signing of the first paréage which provided that Andorra's sovereignty be shared between the count of Foix (whose title would ultimately transfer to the French head of state) and the Bishop of Urgell, in Catalonia. This gave the principality its territory and political form.
Over the years, the French co-title to Andorra passed to the kings of Navarre. After Henry of Navarre became King Henry IV of France, he issued an edict in 1607 that established the head of the French state and the Bishop of Urgell as co-princes of Andorra. In 1812–13, the First French Empire annexed Catalonia and divided it in four départements, with Andorra
