A training begun in early boyhood made the rider almost one with his steed; and he could use his weapons with equal ease and effect whether his horse was stationary or at full gallop, and whether he was advancing towards or hurriedly retreating from his enemy.

His supply of missiles was almost inexhaustible, for when he found his quiver empty, he had only to retire a short distance and replenish his stock from magazines, borne on the backs of camels, in the rear.

It was his ordinary plan to keep constantly in motion when in the presence of an enemy, to gallop backwards and forwards, or round and round his square or column, never charging it, but at a moderate interval plying it with his keen and barbed shafts which were driven by a practised hand from a bow of unusual strength.

Clouds of this light cavalry enveloped the advancing or the retreating foe, and inflicted grievous damage without, for the most part, suffering anything in return.
But this was not the whole.

In addition to these light troops, a Parthian army comprised always a body of heavy cavalry, armed on an entirely different system.