Obsidian, a black volcanic glass, was first recognized by Colin Renfrew and his colleagues J.E. Dixon and J.R. Cann in the 1960s as a uniquely sensitive indicator of prehistoric trade, both because of the great desirability of this material before the use of metals, and also because the trace-elements it contains are usually diagnostic of individual sources. Based on data extracted from M.-C. Cauvin et al., L'obsidienne au Proche et Moyen Orient: du volcan à l'outil (Oxford: BAR Int. Ser. 738), maps indicate the flows of material from two major source-areas.

Satellite images provide a convenient means of understanding why early sites were chosen for settlement, and of visualising the routes that linked them. These two factors (location amongst critical resources, and position in wider networks) interacted with each other: oases were occupied both because of their local advantages, and also because they acted as stepping-stones on routes carrying desirable materials over long distances. This presentation applies these arguments to a critical problem in prehistoric archaeology: where precisely did farming first emerge in western Asia?