The two countries mentioned in the question belong to the Russian Federation, and the "Republic" is the administrative entity with the highest degree of autonomy within the federal jurisdiction, which is higher than the "autonomous region" of China; At the same time, Russia also has the concept of "autonomous region", which is equivalent to China's "autonomous prefecture", but slightly higher.
Back to the problem of Mongols. In China, the definition of Mongolians is based on the similarities of language and religious traditions, as well as the ethnic groups that are consistent with the concept of Mongolians in history. But according to the western division method, this is impossible to achieve.
For example, the two autonomous ethnic groups in your question are Tuva and Buryatia Mongols, which are divided into two ethnic groups outside China, while in China, they both belong to "Mongols". So the total population you mentioned is quite difficult to count.