Topological insights into the diachrony of ancient road networks: Exploratory predictive modelling in the Andean highlands

As the footprint of the movements and interactions that shape territories, road networks constitute a key archaeological feature for studying long term territorial dynamics. However, most archaeological research has focused on individual routes at specific periods, and little has been done so far to research road networks' long-term evolution at a regional scale. While the widespread availability of high-resolution aerial imagery facilitates recording ancient road networks in details, their chronological diagnostic remains challenging since road architecture is generally not a reliable proxy and direct stratigraphic dating is limited to very few contexts. This paper outlines a modelling approach to assess the chronology of roads based on their topological relationship with dated settlements, an idea formulated long ago but never technically implemented so far. It presents a case study on a regional road network's evolution during the last millennium, in the arid highlands of northern Chile, which conserve abundant traces and infrastructure of the settlement patterns and movement systems of its ancient territories. The case study shows the potential of this predictive modeling approach to preliminarily assess the chronology of individual road segments, as well as to visualize and characterise the evolution of the whole network through the historical periods. The basic models implemented in this paper to derive probabilities could be further refined for more specific contexts and hypotheses, and applied to many deserts and mountain regions worldwide, where ancient roads and pathways frequently accumulate as part of long-term territorial dynamics.