To a certain extent they were cannibals.

It was their custom not to let the aged among them die a natural death, but, when life seemed approaching its natural term, to offer them up in sacrifice,--and then boil the flesh and feast on it.
This mode of ending life was regarded as the best and most honorable; such as died of disease were not eaten but buried, and their friends bewailed their misfortune.
It may be added to this that we have sufficient reason to believe that the Massagetse and the other nomads of these parts regarded the use of poisoned arrows as legitimate in warfare, and employed the venom of serpents, and the corrupted blood of man, to make the wounds which they inflicted more deadly.
Thus, what was threatened was not merely the conquest of one race by another cognate to it, like that of the Medes by the Persians, or of the Greeks by Rome, but the obliteration of such art, civilization, and refinement as Western Asia had attained to in course of ages by the successive efforts of Babylonians, Assyrians, Medes, Persians, and Greeks--the spread over some of the fairest regions of the earth of a low type of savagery--a type which in religion went no further than the worship of the sun; in art knew but the easier forms of metallurgy and the construction of carts; in manners and customs, included cannibalism, the use of poisoned weapons, and a relation between the sexes destructive alike of all delicacy and of all family affection.

The Parthians were, no doubt, rude and coarse in their character as compared with the Persians; but they had been civilized to a certain extent by three centuries of subjection to the Persians and the Greco-Macedonians before they rose to power; they affected Persian manners; they patronized Greek art, they appreciated the advantages of having in their midst a number of Greek states.

Had the Massagetse and their kindred tribes of Sakas, Tochari, Dahse, Yue-chi, and Su, which now menaced the Parthian power, succeeded in sweeping it away, the general declension of all which is lovely or excellent in human life would have been marked.
Scythicism would have overspread Western Asia.

No doubt the conquerors would have learned something from those whom they subjected; but it cannot be supposed that they would have learned much.