The article covers the contents of an Oirat historical work named «The story is about how the rulers of Genghis managed the state and maintained the khanate rule» written in «todo bichig» (clear script). It mainly deals with the ethnic history of the Oirats (Western Mongols) and narrates the origin of their major ethnic components (the Khoshuts, the Dzungars, the Derbets, the Khoits and the Torghuts), the genealogies of their princes and their mutual relationship with each other in the 17th - the 1st half of the 18th century. It is particularly remarkable that there was no ethnonym “Oirat” used in the work, it was replaced with a new collective ethnonym “Eleuth”. According to its anonymous author, the fact that those considered to be direct successors of the ruler Genghis, the united Mongol tribes, including the Oirats, were shattered and scattered, is a common misconception. The author finishes the work written in a span of ten years (1858-1868) by describing the events which led to the conquest of the Dzungar Khanate by the Qing empire in 1755-1758. Despite its fragmentary nature, the work contains the facts which after their verification and comparison can not only clarify the history but enrich the sources for research information. However, they can be considered reliable, since they are confirmed by reference to the other sources
