The Kerretes were probably essentially of Basque and Aquitanian-related stock, as the Iberian clans who mixed with the native inhabitants can have comprised only small numbers of people.

[citation needed] The main oppidum of the Kerretes, commanding the whole country, was called Kere and was built on the hill above the modern-day village of Llívia (a Spanish exclave in French territory).

At the end of the Roman Empire, Julia Lybica entered a period of decadence, and lost much of its importance.

It is around this time that the town of La Seu d'Urgell (in Catalonia, but outside of Cerdanya) started to replace Julia Lybica as the main center of population in that area of northern Catalonia, and in the 6th century when the diocese (bishopric) of Urgell was founded, Cerdanya was inside its limits.

Devastated by the Vandals and other Germanic tribes, Cerdanya was part of the Visigothic kingdom of Toulouse and later Toledo, until eventually it was conquered by the Muslims.

However, Uthman ibn Naissa came next under Umayyad attack and the Berber lord was defeated, opening the way to Abdul Rahman Al Ghafiqi's expedition into Aquitaine.

During Abd al-Rahman I's military campaign across the Ebro region (781), the Cordovan commander received the submission of Ibn Belaskut, or Galindo Belascotenes, in Cerdanya.

The counts of Cerdanya were great patrons of abbeys, most famously Saint-Michel de Cuxa (Catalan: Sant Miquel de Cuixà), dating back to the 10th century and located in Conflent, and Saint-Martin-du-Canigou (Catalan: Sant Martí del Canigó), dedicated by Count Guifred of Cerdanya in 1009.

Hix, the place where the counts of Cerdanya resided, is now a village inside the commune of Bourg-Madame on the French side of the border.

Despite the split between France and Spain, ties remain between families on both sides of the border, with frequent travel from one country to the other.

All municipalities of Baixa Cerdanya are part of the Catalan region of Alt Pirineu, this one itself divided between the Spanish provinces of Lleida and Girona.

[9] Due to La Cerdanya's close proximity to Andorra and France, its residents also enjoy skiing in "Font Romeu," "Formigueres," "Les Angles," and "Grandvalira.