Why Did Cities Evolve in Gharb Al-Andalus? Network analysis as a potential method for charting city growth

The Muslim presence in the Iberian Peninsula has been closely associated with urban centres since the 8th century. Using an approach based on Network Theory, the purpose of this article is to understand and debate the influence that various cities exerted on each other through communication routes during the Islamic presence in the Gharb Al-Andalus – now in modern-day Portugal - and how this influence affected the growth of those cities. This study intends to use statistical analysis based on Network Theory and on its centrality measures in order to build a network of geographical relationships between the cities of the Gharb Al-Andalus. The study of these centrality measures indicates that mutation in the importance of such cities might result from their geographic location, but also by the influence that each city had over the nearest ones. The theory is by measuring the centrality value of a city at a certain moment, it would be possible to indicate the probability that the city would either grow or decline in the subsequent period. This influence on growth was surely due to political, military, religious or commercial contacts but, likewise, by the different ways cities were connected (terrestrial, fluvial and maritime).