Although lightly armed and somewhat lacking in equipment, don't underestimate the value of these fierce warrior-bands. Although they are fairly weak if surrounded by infantry, their proficiency with javelins means that they are extremely deadly when pitted against enemy cavalry, thus making them ideal when facing enemies dependent on horsemen such as the Numidians or Sarmatians. Not only are they handy at throwing their javelins as fast as the naked skirmishers of the Celtic nations, they also have the benefits of added armour and strong anti-cavalry attack, thus making them ideal for defending against enemy cavalry. Just remember to keep them away from units that can swarm them, particularly light ranged infantry, and they can hold their own against a good number of enemies.
Because of the rugged terrain of their home in the highlands of the Elburz range and the apparent poverty thereof, the people of Hyrcania grew to become a rugged and fierce people who managed to repulse many invaders of their lands, earning them a place in history as mercenaries well into the Middle Ages.