  For gauge theories which admit a dual string description, we analyze deep
inelastic scattering at strong 't Hooft coupling and high energy, in the
vicinity of the unitarity limit. We discuss the onset of unitarity corrections
and determine the saturation line which separates weak scattering from strong
scattering in the parameter space of rapidity and photon virtuality. We
discover that the approach towards unitarity proceeds through two different
mechanisms, depending upon the photon virtuality Q^2 : single Pomeron exchange
at relatively low Q^2 and, respectively, multiple graviton exchanges at higher
Q^2. This implies that the total cross-section at high energy and large Q^2 is
dominated by diffractive processes. This is furthermore suggestive of a
partonic description where all the partons have transverse momenta below the
saturation momentum and occupation numbers of order one.
