  We propose a concept of disordered resonant media, which are characterized by
random variations of their parameters along the light propagation direction. In
particular, a simple model of disorder considered in the paper implies random
change of the density of active particles (two-level atoms). Within this model,
the effect of disorder on self-induced transparency (SIT) is analyzed using
numerical simulations of light pulse propagation through the medium. The
transition from the SIT to localization regime is revealed as well as its
dependence on the disorder level, atom density, medium thickness, and period of
random variations.
