The once free trade between the natives of the high valleys, even in times of war, gradually became a smuggling or illegal activity as the states delimited the borders and controlled the movement of goods and people between the two sides of the Pyrenees. In this way, what had hitherto been a flourishing and permitted trade became illegal smuggling.

The great adventure of smuggling, especially in Aragon, did not begin until the 19th century, when the state, which constantly saw the ineffectiveness of criminal laws and the work of the army, created a definitive customs law and a paramilitary corps to enforce it.

In the surveillance of the Sallent border line, they took advantage of old disused buildings, such as the Romanesque hospital of Socotor, to convert it into a carabinieri post. From there they controlled the passes of Portalet and Peiralún or Puerto Viejo, the latter being used regularly before the construction of the road. There were also barracks in the village, the Portalé and in the Formigal hut (now disappeared).

Peiralun is a summit on the border between Spain and France, at an altitude of 2100 m, very close to Portalet, where we can see the muga 311, which was one of the points separating the two countries.

The goods that were smuggled varied greatly according to the circumstances and needs of the two smuggling nations.

Cloth, tow, bacon, bacon, shearlings, horses and pigs were smuggled into Spain, followed by cod, salted sardines, butter and cheese.

Stockings, wool, oil, wine and salt were taken to France.