Alternatively the Chinese word for Barbarian was Ta-Ta and historians just prefer to use the word Tatar, it all depends which books you wish to believe. Not saying yours are wrong (and I agree that the widespread obsession with all things Tartaria is overblown) but I am absolutely confident turko-mongolic steppe people were a far bigger deal than what is commonly talked about these days. The history of how the land companies acted throughout Asia and the world at large is far from subtle.
As to what lands they owned...
That is pretty far south for Mongolia. I guess it may have been considered Mongolia at one time, or maybe we are talking Russia as in the whole fucking USSR plus a chunk of China, but they seemed like major players.