The Choros (or Tsoros) was the ruling clan of the Dzungars and Dorbet Oirats and once ruled the whole Four Oirats. They founded the Dzungar Khanate in the 17th century. According to a myth, their chiefs reckoned their descent from a boy nourished by a sacred tree.
In the late 14th century, the Oirats appeared as dominant power against the Eastern Mongols. The ruling clan of the Four Oirat was Choros at the time. Under their leadership, the Western Mongols established their authority over all Mongolia proper and defeated the Jurchens, the Tuvans, and the Moghulistanis.
In 1455 other Oirat tribes overthrew the Choros Khan Esen Tayishi who had enthroned himself Khagan of the Mongols. About 1620 the Choros scattered after bitter fighting with the Khalkha Altan Khan. The Khalkha and south-western Inner Mongolian princes repeatedly looted them from 1552 to 1628, forcing them to migrate further west. Some of the Choros fled with a body of the Dorbet Oirats northward into Siberia and present-day Barnaul. But they crushed the Khalkha Altan Khan; and made an alliance with the northern Khalkhas in 1640.
By 1690 three Oirat states had emerged: the Khoshut, Kalmyk and Dzungar Khanates. The majority of the Choros with the Dorbeds and the Khoids settled in the region of the Black Irtysh, the Urungu, the Imil, and the Ili, forming the Dzungar Khanate. The Zunghar Khanate was ruled by the Dorbed and the Choros, displaced the Khoshuds in their homeland Dzungaria. Although, they reached their peak in the late 17th century, they began to disintegrate after Galdan's wars with the Qing. The Choros were defeated in 1697 and 1771; and they were annexed by the Qing dynasty. The Western Mongols under the Choros princes who submitted to the Qing became Öölds.
- Fred Walter Bergholz-The partition of the steppe, p.353