Tarkhan functioned as a designation within the military structure of the Kaleesh species' army, specifically for the kolkpravis. This title was given to the officer commanding a kolkpravis [horde], a unit composed of 100 kamen – each kamen containing between two and forty Kaleesh warriors.
The term tarkhan initially appeared in Galaxy at War, a 2009 sourcebook created by Wizards of the Coast for the Star Wars Roleplaying Game.