The Treaties of Good Correspondence were agreements drawn up under the Ancien Régime by the Basques of France and those of Spain, designed to guarantee the continuity of their economic relations despite the wars between the two countries.

Other examples of the same economic pragmatism can still be found today all along the border between Spain and France, the latest dating from 1957 between Vera de Bidassoa and Sare.

Arthur de Boislisle noted: "You know how difficult it is to prevent the people of Labourd from following their ancient customs; nor are you unaware that, at whatever price, the inhabitants of the mountains of France and Spain wish to consecrate their union, which the fiercest wars have never been able to interrupt [...]".

[1] The first treaties, whose actual title is "Treaties of Commerce or Good Correspondence between the Inhabitants of the Government of Bayonne and the Bailiwick of Labourd and those of the Provinces of Guipuscoa and the Seigniory of Biscay[ED 1]", seem to date from the end of the thirteenth century (1294) and the beginning of the fourteenth century (1306, 1309, 1311 and 1328)[Note 1][ED 2] - at the time, the aim was to regularize the restitution of pinnaces stolen by the inhabitants of Bayonne or Biarritz, as well as those of Santander or Castro-Urdiales.

[4] During this century, we should note the treaty of 1719, established during the Regent's war against Philip V, and that of 1795, during the occupation of Guipuscoa by Directory troops, concluded with Biscay.

[Note 3] It also stated that "no act of war may take place in this zone [...]" and that "if two enemy ships meet in the same port, one may not leave until twenty-four hours after the other [...]".

After the first four articles, which set out certain general provisions,[Note 5] the conventions of commerce and navigation themselves are dealt with, in particular the establishment of a passport which "legitimizes the voyage and protects the ship and merchandise from capture".

Although these treaties appear to have been negotiated directly between the deputies of the Basque provinces belonging to two different countries, in the absence of any representative of the royal authority, this freedom is only apparent.

[ED 13] The same was true for the Spanish side, since article 12 of the 1653 treaty stipulated that "it shall be reciprocally ratified by Their Most Christian and Most Catholic Majesties" and registered in the "Admirautez de France et dans celles d'Espagne".

[ED 14] The ability to sign such cross-border treaties can be found further east, on the Franco-Spanish border, since, according to Léon Cadier, the Béarnais possessed this same faculty, also attributed by the fueros of the Val d'Aran to its inhabitants.