The northwestern limit of the Seville domains constituted a complex frontier space of high potencial tension throughout the Late Middle Ages. Once the conquest of this historical territory was over, the council of Seville promotes the definition of a castral system destined to guarantee the guard and defense of its extensive territory. The Galician Band constituted a large network of fortifications who knew how to incorporate the existing ones and build new castles, which responded to an adaptive logic based on the poliorcetic and geopolitical requirements. The geospacial analysis carried out in this research, implemented through GIS, allowed contrasting certain hypotheses sustained from historiography regarding the territorial implementation strategy of these passive defenses. The detailed analysis of the intervisibility relations between the fortifications of the Galician Band, allowed to define its spatial link. The analyzed castramental spaces are hierarchized, presenting a progressive stratification from the border spaces into the deep lands of the Council, following a spatial pattern that allows the strategic control of the main paths of territorial penetration.