Original: This reference apparently alludes to the precarious political scenario following the collapse of Mauryan and Sunga dynasties in northern India and its occupation by foreign hordes of the Shakas, Yavanas, Kambojas and Pahlavas.
Simplified: This seems to mean the situation after the Mauryan and Sunga dynasties fell apart and northern India was occupied by foreign armies of the Shakas, Yavanas, Kambojas and Pahlavas.