The work of O. M. Kovalevsky contains a detailed historiography on the history of the East, taking into account the works of Chinese, Arab, Persian, Russian and European scientists; tells about the history of the tribes that once inhabited Central Asia, their relationships and rivalry. The work gives a wide panorama of the military, political and cultural interaction of many peoples; particular attention is paid to the history of Mongolian-Russian-Chinese relations. The time frame of the period under consideration covers several centuries - from the III century. BC e. Until the middle of the XIX century. The monograph of O. M. Kovalevsky is the first in Russian oriental studies generalizing work on the history of the Mongols of such a large historical period. It is valuable historical information and represents an important and informative source on the history of Mongolia and Central Asia. Many of the theoretical conclusions reached by the author remain correct more than a century and a half after writing and interesting for modern researchers.