in the 320s bc, alexander the great conquered the entire achaemenid empire, beginning the hellenistic period. the greek name παροπαμισάδαι or παροπαμισσός was used extensively in greek literature to describe the conquests of alexander and those of the kings of the greco-bactrian kingdom and the indo-greek kingdom, from the 3rd to the 1st centuries bc. (the name possibly comes from an avestan expression for "higher than an eagle can fly").