Quatre-Vallées (i.e. "Four Valleys") (Gascon: Quate-Vaths) was a small province of France located in the southwest of France. It was made up of four constituent parts: Aure valley (Gascon: Aura), Barousse valley (Gascon: Varossa), Magnoac valley (Gascon: Manhoac), and Neste or Nestès valley (Gascon: Nèsta or Nestés).
Originally part of Comminges, the valleys of Aure, Barousse, Neste, and Magnoac were detached from Comminges in the 11th century and were divided between the counts of Aure, vassals of the kings of Aragon, and the counts of Astarac (in Gascony). The line of the counts of Aure ended in 1242 without a male heir, and the county of Aure was inherited by the counts of Labarthe (residing in La Barthe-de-Neste), who by then possessed the three other valleys of Neste, Barousse, and Magnoac. Thus, the four valleys were unified under the counts of Labarthe, and began to be known as Quatre-Vallées. The counts of Labarthe were vassals of the kings of Aragon, and so Quatre-Vallées was part of the kingdom of Aragon.
The Quatre-Vallées were a buffer zone between the county of Comminges and the powerful county of Armagnac (in Gascony), and were coveted by both, until eventually in 1398 they became a possession of the counts of Armagnac. In 1462, Count Jean V of Armagnac ceded the fief of Quatre-Vallées to his incestuous sister Isabelle of Armagnac. Isabelle, who had given her fortune to charities, ended up in utter poverty, and on top of it she became paralyzed with hemiplegia. Taking advantage of her weakness, Gaston de Lyon, Lord of Bezaudun and seneschal of Toulouse, lured the poor Isabelle into selling him the Quatre-Vallées against 5,127 gold crowns (écus d'or), which he never paid, always postponing payment in the hope of a rapid death of Isabelle.
At the same time, in 1475, as the king of France obtained Roussillon from the king of Aragon, the Quatre-Vallées were officially detached from the kingdom of Aragon and entered the kingdom of France. However, they were still not part of the royal domain, and were just one of the many independent fiefs of the kingdom of France.
Eventually, the maneuvering of Gaston de Lyon alerted higher authorities. Gaston de Lyon then sent his private doctor to Isabelle, and this one saw to it that she would not live long enough to embarrass his master. In August 1476, the paralyzed and forlorn Isabelle of Armagnac, who in her youth had been promised to the king of England, died in horrible pain after drinking a potion prepared by the doctor to "cure" her. She was only 45. Gaston de Lyon immediately claimed the Quatre-Vallées. His attitude was so revolting that the duke of Alençon and the duke of Vendôme, relatives of Isabelle of Armagnac, sued Gaston de Lyon to prevent him from obtaining the Quatre-Vallées. The trial lasted for more than a century. At last, ruined and discouraged, the descendants of Gaston de Lyon ceded the Quatre-Vallées to Henry III of Navarre, who owned many Pyrenean fiefs (Béarn, Lower Navarre, Bigorre, County of Foix, Nébouzan).
At the start of the French Revolution, the Quatre-Vallées remained quiet. They had been freed and exempted from feudal taxes and corvées for centuries already, and so they did not demand equality and the end of privileges like the other parts of France did. At first it was planned that Quatre-Vallées would gather with the provinces of Nébouzan and Comminges, and that the three would elect common representatives to the Estates-General in Versailles. The Quatre-Vallées saw this as a breach of their Statutes and autonomy, and they sent a letter of protest to Versailles. Eventually, they were allowed to send their own representative to the Estates-General. This representative was assigned the task of preserving the privileges of the Quatre-Vallées at all cost. However, there was not much he could do when feudalism and all the privileges were abolished by the French National Constituent Assembly in the night of 4 August 1789, and so the Quatre-Vallées lost their old privileges.
The area remained very traditional well into the 20th century, and modernity progressed only slowly. Like the rest of the Pyrenees, Quatre-Vallées suffered a lot from rural exodus. Today, the low population density of the Quatre-Vallées have turned them into a haven for nature lovers and people wishing to discover some of the wildest parts of the Pyrenees, where a spectacular landscape is combined with a rich historical heritage and many old monuments.