Hermandad de las Cuatro Villas
The Hermandad of the Cuatro Villas de la Costa de la Mar ('Brotherhood of the Four Cities'), also cited under the name Cuatro Villas de la Costa de Cantabria, was a medieval and modern administrative entity that grouped the coastal cities of the north of the kingdom of Castile, all of them part of present-day Cantabria; namely, from west to east: San Vicente de la Barquera, Santander, Laredo, and Castro-Urdiales. At the end of the 15th century, it became part of the corregimiento of the Cuatro Villas along with other territories in the north of the Iberian Peninsula.
Source: Wikipedia — Hermandad de las Cuatro Villas (CC BY-SA 4.0)