By the 1st century BC they comprised eleven or so tribes—, , Camarici or Tamarici, Concani, Coniaci or Conisci, Morecani, Noegi, Orgenomesci, Plentuisii, Salaeni, Vadinienses, and Vellici or Velliques—gathered into a tribal confederacy with the town of "Aracillum" (Castro de Espina del Gallego, Sierra del Escudo – Cantabria), located at the strategic Besaya river valley, as their political seat. Other important Cantabrian strongholds included "Villeca/Vellica" ( – Palencia), "Bergida" (Castro de – Palencia) and "Amaya/Amaia" ( – Burgos). In early 1st century BC, the Cantabri began to play a double game by lending their services to individual Roman generals on occasion but, at same time, supported rebellions within Roman Spanish provinces and carried out raids in times of unrest. This opportunistic policy led them to side with Pompey during the final phase of the Sertorian Wars (82–72 BC), and they continued to follow the Pompeian cause until the defeat of his generals Afranius and Petreius at the battle of "Ilerda" (Lérida) in 49 BC. Prior to that, the Cantabri had unsuccessfully intervened in the Gallic Wars by sending in 56 BC an army to help the Aquitani tribes of south-eastern Gaul against Publius Crassus, the son of Marcus Crassus serving under Julius Caesar.