The propagation of light through atomic vapours gives rise to a variety of interesting effects including self-induced transparency (SIT), optical simultons and the formation of transient trains of light pulses. In this thesis, we investigate such effects using numerical simulations and theoretical techniques. We first study the dynamics of SIT solitons, comparing our numerical results with analytical predictions and previous numerical studies. We then explore the propagation of continuous wave (CW) fields, focusing on the transient dynamics that occur during and shortly after the fields are turned on. We show that a CW field breaks up into a train of pulses as it propagates into a medium, but that these oscillations are dampened in the presence of homogeneous broadening. In the absence of homogeneous broadening, we observe that the pulses become increasingly separated as the field moves deeper into the medium, in contrast to what was concluded in previous studies. We also present original results in which transient pulse trains are seen to form from two CW fields propagating through a medium of three-level V-type resonators and discuss the mechanisms behind their formation.