What does "koulan" mean?

Koulan: A wild horse (Equus, or Asinus, onager) inhabiting the plants of Central Asia; -- called also gour, khur, and onager. [Written also kulan.] Note: It is sometimes confounded with the dziggetai, to which it is closely related. It is gray in winter, but fulvous in summer. It has a well defined, dark, dorsal stripe, and a short, erect mane. In size, it is intermediate between the horse and ass.