  This chapter examines the geographical meaning of the Sahel, its fluid
boundaries, and its spatial dynamics. Unlike other approaches that define the
Sahel as a bioclimatic zone or as an ungoverned area, it shows that the Sahel
is primarily a space of circulation in which uncertainty has historically been
overcome by mobility. The first part of the paper discusses how pre-colonial
empires relied on a network of markets and cities that facilitated trade and
social relationships across the region and beyond. The second part explores
changing regional mobility patterns precipitated by colonial powers and the new
approach they developed to control networks and flows. The third part discusses
the contradiction between the mobile strategies adopted by local herders,
farmers and traders in the Sahel and the territorial development initiatives of
modern states and international donors. Particular attention is paid in the
last section to how the Sahel was progressively redefined through a security
lens.
