Zasagt Khan

It was one of four Khalka khanates that emerged from remnants of the Mongol Empire after the death of Dayan Khan's son Gersenji Khongtaiji in 1549.

His younger brother Tsevenjab succeeded as the new khan, however, Khalka was invaded by Dzungar Mongolian forces under Galdan Boshugtu Khan in the next year, Tsevenjab had to flee to Ulanqab where he pledged fealty to the Kangxi Emperor of the Qing China.

In the next year, Khalka was divided into three zams (зам), the area of Zasagt Khan aimag was named "Khalka Right Zam" (Mongolian: Халхын өрнө зам, Chinese: 喀爾喀西路).

[4] Since 1728, each aimag was governed by aimag congress chigulgan (чуулган) comprising the lords of the khoshuns; the chigulgan daruga (чуулган дарга - official presiding the congress) was appointed from the khoshun lords by the Qing government.

the congress of Zasagt khan aimag was called the "Zag golyn ekh Binderiyaa nuuryn chuulgan" (Заг голын эх Биндэръяа нуурын чуулган, 札克畢拉色欽畢都爾諾爾盟), which was held every three years at the source of Zag Gol River (Заг гол).